Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “SPL”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMed2003

Deriving the real-ear SPL of audiometric data using the "coupler to dial difference" and the "real ear to coupler difference".

OBJECTIVE: The purpose of the study was to compare the measured real-ear sound pressure level (SPL) of audiometer output with the derived real-ear SPL obtained by adding the coupler to dial difference (CDD) and real-ear to coupler difference (RECD) to the audiometer dial reading. DESIGN: The real-ear SPL and RECD were measured in one ear of 16 normally hearing subjects using a probe-tube microphone. The CDD transform and the RECD transfer function were measured in an HA1 and an HA2 2-cc coupler using an EAR-LINK foam ear-tip or a customized earmold. The RECD transfer function was measured using the EARTone ER 3A and the Audioscan RE770 insert earphone. RESULTS: The procedures were very reliable with mean differences on retest of less than 1 dB. The mean difference between the measured and derived real-ear SPL was generally less than 1 dB and rarely exceeded 3 dB in any subject. CONCLUSIONS: The CDD measured for an individual audiometer and the RECD measured for an individual ear can be used to derive a valid estimate of real-ear SPL when it has not been possible to measure this directly.

Acoustic Impedance Tests↗
PubMed2003

Impact on hearing aid targets of measuring thresholds in dB HL versus dB SPL.

Audiometric measurements are traditionally made in dB HL, which by definition are specified relative to the sound pressure level (SPL) in a coupler. Real-ear dB SPL is then estimated by applying an average ear transform to the coupler value. However, individual variation in ear canal acoustics and variations in transducer placement strongly influence the dB SPL of signals arriving at the eardrum. In this paper, data from 1814 ears are presented, showing that the distribution of eardrum dB SPL for a fixed signal level varies across ears and across frequency by as much as 40 dB. The impact of this variance upon hearing aid targets computed with the NAL-NL1 fitting algorithm is examined by comparing the targets obtained from using an average transform with those obtained when audiometric data in dB SPL are obtained by applying individually measured real-ear-to-coupler difference (RECD) values to dB HL thresholds. The impact can be considerable.

Acoustic Stimulation↗
PubMed1997

Conversion of a head-mounted microphone signal into calibrated SPL units.

A method is reviewed for conversion of a microphone signal into calibrated Sound Pressure Level (SPL) units. The method follows American National Standards Institute (ANSI) standard for S1.4 SPL meters and requires an accurate SPL meter and an accurate calibration sound source for conversion. Accuracy and validation data from test signals and human phonation are provided. The results indicate that under typical speech conditions, an absolute accuracy of plus or minus 1.6 dB (type 1 SPL meter) can be obtained with a miniature head-mounted microphone.

Amplifiers, Electronic↗
PubMed1998

Data on subglottal pressure and SPL at varied vocal loudness and pitch in 8- to 11-year-old children.

Phonation threshold pressure has been defined as the minimum subglottal pressure to generate phonation. Previous research has indicated that children may habitually employ higher subglottal pressures than adults. In the present investigation sound pressure level (SPL) and subglottal pressures at different pitch levels were measured at and above phonation threshold in nine children. Phonation threshold values were scattered in reasonable agreement with Titzes' prediction, although a discrepancy was noted regarding the frequency dependence in some voices. At normal conversational loudness and loudest level of phonation the children's Ps values were between two to four and four to eight times the predicted threshold values, respectively. At normal conversational loudness and habitual pitch subglottal pressures were lower than those previously observed for children, but similar to those found for female adults. The SPL in softest and loudest phonation were somewhat lower as compared to previous phonetogram data for children and for female adults. At normal loudness and habitual pitch the SPL values were similar to those of female adults. For a doubling of Ps mean SPL increased by 10.5 dB on the average.

Child↗
PubMed1996

Distinct phosphate backbone contacts revealed by some mutant peptides of zinc finger protein Spl: effect of protein-induced bending on DNA recognition.

By using some mutant peptides of transcription factor Spl, phosphate backbone contacts with the DNA binding protein containing three zinc fingers have been investigated by alkylation interference, circular permutation, DNase I footprinting, and methylation protection methods. The ethylation interference analyses of Spl(R565S) and Spl(K595S) mutants demonstrate that arginine at 565 position and lysine at 595 position interact with the phosphate between G(3) and G(4) and with the phosphate between G(9) and G(10) in GC-box DNA, respectively. On the basis of the experimental results for Spl(K535G), Sp1(537-623), and Sp1(530-623), lysine and glutamine at 535 and 536 positions have been clarified to be in contacts with phosphate between G(7) and G(8) and with phosphate outside GC-box, respectively. In particular, glutamine at the N-terminal side of zinc finger 1 is a key amino acid residue to induce DNA bending and also participates in total base specificity of Sp1. The present study strongly indicates that (1) each zinc finger is not independent for the DNA interaction with Sp1 and (2) DNA base recognition of the zinc finger protein is influenced by local conformational change of DNA induced by the protein binding.

Amino Acid Sequence↗
PubMed1992

The Enhancer of split [E(spl)] locus of Drosophila encodes seven independent helix-loop-helix proteins.

The E(spl) locus is thought to participate in a cell interaction mechanism that controls the choice of many cell fates during Drosophila development, including the segregation of neural precursors. Previous studies have demonstrated that E(spl) is defined by two groups of closely related transcripts, (i) a cluster of three transcripts encoding proteins bearing a helix-loop-helix (HLH) motif and (ii) a single-copy gene encoding a nuclear protein containing repeated motifs first identified in the beta subunit of guanine nucleotide-binding proteins. Both groups interact genetically with the Notch locus, which codes for a transmembrane protein. We report the structure of four additional HLH-encoding genes that reside in the E(spl) complex and provide evidence that we have now identified all the remaining members of the E(spl) HLH cluster.

Amino Acid Sequence↗
PubMed2001

Use of the 'real-ear to dial difference' to derive real-ear SPL from hearing level obtained with insert earphones.

The electroacoustic characteristics of a hearing instrument are normally selected for individuals using data obtained during audiological assessment. The precise inter-relationship between the electroacoustic and audiometric variables is most readily appreciated when they have been measured at the same reference point, such as the tympanic membrane. However, it is not always possible to obtain the real-ear sound pressure level (SPL) directly if this is below the noise floor of the probe-tube microphone system or if the subject is unco-operative. The real-ear SPL may be derived by adding the subject's real-ear to dial difference (REDD) acoustic transform to the audiometer dial setting. The aim of the present study was to confirm the validity of the Audioscan RM500 to measure the REDD with the ER-3A insert earphone. A probe-tube microphone was used to measure the real-ear SPL and REDD from the right ears of 16 adult subjects ranging in age from 22 to 41 years (mean age 27 years). Measurements were made from 0.25 kHz to 6 kHz at a dial setting of 70 dB with an ER-3A insert earphone and two earmould configurations: the EAR-LINK foam ear-tip and the subjects' customized skeleton earmoulds. Mean REDD varied as a function of frequency but was typically approximately 12 dB with a standard deviation (SD) of +/- 1.7 dB and +/- 2.7 dB for the foam ear-tip and customized earmould, respectively. The mean test-retest difference of the REDD varied with frequency but was typically 0.5 dB (SD 1 dB). Over the frequency range 0.5-4 kHz, the derived values were found to be within 5 dB of the measured values in 95% of subjects when using the EAR-LINK foam ear-tip and within 4 dB when using the skeleton earmould. The individually measured REDD transform can be used in clinical practice to derive a valid estimate of real-ear SPL when it has not been possible to measure this directly.

Acoustic Stimulation↗
PubMed1986

Acoustics of ear canal measurement of eardrum SPL in simulators.

The effect of standing waves on the ear canal measurement of eardrum sound pressure level (SPL) was determined by both calculation and measurement. Transmission line calculations of the standing wave were made using the dimensions of the ANSI S3.25-1979 ear simulator and three different eardrum impedances. Standing wave curves have been obtained for the standard eardrum impedance at 1-kHz intervals in the range of 1-8 kHz. The changes in standing wave position due to each of the three eardrum impedances and their effects on ear canal measurements of SPL were computed for each of the eardrum impedances. Ear canal SPL measurements conducted on simulators modified to correspond to the eardrum impedances used in the calculations were compared to the computed values. Differences between eardrum SPLs and those measured at different locations in the ear canal approached a standing wave ratio (SWR) of 10-12 dB as the position of the measuring probe approached the standing wave minimum at each frequency. These maximum differences compared favorably with data developed by other investigators from real ears. Differences due to the eardrum impedance were found to be significant only in the frequency region of 2-5 kHz. Calibration of probes in a standard or modified ANSI simulator at the same distance from the eardrum as in the real ear reduces the eardrum SPL measurement errors to those resulting from differences in eardrum impedance.

Acoustic Stimulation↗
PubMed1995

Suppressor of hairless, the Drosophila homologue of RBP-J kappa, transactivates the neurogenic gene E(spl)m8.

Suppressor of Hairless[Su(H)], the Drosophila homologue of RBP-J kappa is a novel type of sequence-specific DNA binding protein without known motifs, and highly conserved in various organisms. Su(H) regulates peripheral nervous system (PNS) development. Recently Su(H) was suggested to participate in the Notch-mediated signal transduction pathway. We show here that the Su(H) protein binds to TGTGGGAA sequence located 616 base-pairs upstream of the transcription initiation site of the Enhancer of split [E(spl)]m8 gene which is mapped to the terminus of the genetic cascade of the neurogenic genes. Su(H) transactivates the E(spl)m8 promoter not only in cultured Drosophila cells but also in vivo. The present study bridges the biochemical gap between Notch and E(spl) in the neurogenic gene cascade including Delta, Notch, deltex, Su(H), Hairless and E(spl).

Alleles↗
PubMed1984

A probe earmold system for measuring eardrum SPL under hearing-aid conditions.

A miniature probe-microphone assembly for use with earmolds was developed to measure the sound pressure level (SPL) of a signal at the eardrum under hearing-aid conditions. The probe-earmold (PE) system was designed with the earmold as an integral part of the acoustic measurement system so that no part of the probe itself projects into the ear canal. Data obtained during a previous investigation with an ear simulator indicated that the PE system could be used to measure eardrum SPL accurately (+/- 3 dB) up to 6.0 kHz. In the current investigation, a behavioral experiment was conducted to validate the accuracy of the PE system on human ears. Comparisons were made between pure-tone thresholds obtained with a conventional earphone and those measured by the PE system using a hearing-aid receiver into an earmold-occluded ear. The basis for the study was the premise that the estimates of the eardrum SPL obtained from pure-tone thresholds are equivalent when the thresholds are determined by sound generated by an earphone into an unobstructed ear or by a hearing aid receiver into an earmold-occluded ear. Results of the study showed no statistically significant differences between the thresholds as determined by the two procedures confirming the simulator data. These results on human ears, together with the physical measurements in a simulator, suggest that the PE system can be used to measure eardrum SPL up to 6.0 kHz in an occluded ear.

Acoustic Impedance Tests↗
PubMed2026

The SPL-family transcription factor MpSPL3 orchestrates the proper regulation of vegetative and reproductive programs in Marchantia polymorpha.

SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) genes encode plant-specific transcription factors that are widely distributed across the plant kingdom. In angiosperms, the multimember SPL family regulates various biological processes, including vegetative-to-reproductive phase transition, inflorescence architecture, and lateral organ development. In contrast, the liverwort Marchantia polymorpha genome encodes only four SPL genes, with functional studies available only for microRNA-targeted members, MpSPL1 and MpSPL2. MpSPL1 was shown to control the meristem dormancy to modulate the thallus architecture, whereas MpSPL2 was found to promote the transition from vegetative-to-reproductive phase. Here, we investigate the impact of the MpSPL3 gene on M. polymorpha development. We demonstrate that MpSPL3 influences coordination of the vegetative growth and the reproductive phase transition. Knockout of MpSPL3 leads to strong growth retardation with disordered thallus morphology, reduced gemma cup number, and, most strikingly, complete loss of gametangiophore formation. Interestingly, overexpression of MpSPL3.2, the shorter isoform, has no detectable morphological effect, whereas the overexpression of MpSPL3.1, the longer isoform encoding a protein with an additional 61-aa long fragment, results in a delay in timing and reduced efficiency of gametangiophore production. Moreover, all the observed developmental abnormalities might be a consequence of the altered expression of genes essential for proper vegetative development and responsible for germ cell specification in MpSPL3 knockout and overexpression plants. Altogether, our findings demonstrate that MpSPL3 is important in regulating gametophyte development and ensuring reproductive success in M. polymorpha.

Marchantia↗
PubMed2005

Sphingolipid-to-glycerophospholipid conversion in SPL-null cells implies the existence of an alternative isozyme.

Sphingosine-1-phosphate (S1P) lyase catalyzes the cleavage of the bioactive lipid molecule S1P to phosphoethanolamine and hexadecenal, both of which are utilized as glycerophospholipid precursors. Until now, only one gene, SPL, has been identified as encoding a S1P lyase. In the present study, SPL-null F9 cells were able to convert radiolabeled dihydrosphingosine to glycerophospholipids, albeit at much lower efficiency than parent cells. Lysates prepared from the SPL-null cells exhibited weak but significant dihydrosphingosine-1-phosphate lyase activity in vitro. These results provide evidence of the existence of an alternative S1P lyase.

Aldehyde-Lyases↗
PubMed1979

Voicing duration and vocal SPL changes associated with stuttering reduction during singing.

This study was conducted to determine if stuttering reduction during singing is associated with increased voicing duration and increased vocal SPL. Eight moderate to severe stutterers comprised the experimental group. Eight normal speakers, matched pairwise with the stutterers for sex and age, served as controls. Pre-experimental testing indicated that all subjects knew from memory the melody of the well-known song "Home on the Range." Subsequently, subjects were asked to read aloud and sing altered lyrics of this song to the conventional melody. Results showed that from reading to singing, disfluency frequency decreased significantly among the stutterers. Both groups of subjects significantly increased voicing durations across the two conditions, but only the normal speakers increased vocal SPL during song. These results indicated that the reduction in stutterers' disfluency (stutterings included) during singing was attended by an altered pattern of vocalization that included an increase in voicing duration, but no significant change in vocal SPL. These findings are discussed with reference to vocal tract dynamics, especially those that might promote higher levels of fluency among stutterers.

Adolescent↗
PubMed2001

Spl phosphorylation induced by serum stimulates the human alpha2(I) collagen gene expression.

Serum has been known to stimulate collagen production by dermal fibroblasts. As part of an ongoing study of the molecular mechanisms of collagen production, we have investigated transcriptional regulation of the human alpha2(I) collagen gene by serum in human dermal fibroblasts. Serum responsive elements were mapped by deletion analysis between bp -353 and -264, and between -148 and -108 in the alpha2(I) collagen promoter. Further functional analysis of the alpha2(I) collagen promoter containing various substitution mutations revealed that serum stimulation of this promoter is mediated equally by a GC-rich region located between bp -303 and -271 and by the TCCTCC motif located between bp -123 and -128, both of which constitute binding sites for transcription factor Spl and Sp3. No differences were observed in electrophoretic mobility shift assays between unstimulated and serum stimulated fibroblasts. The Spl inhibitor mithramycin blocked stimulation of the alpha2(I) collagen promoter activity by serum. Furthermore, immunoprecipitation analysis showed that serum stimulation increased Spl phosphorylation. In conclusion, this study characterized response elements that mediate serum stimulation of the human alpha2(I) collagen promoter and suggests that serum stimulation was mediated via Sp1/Sp3 binding sites in this promoter.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1993

Drosophila evolution challenges postulated redundancy in the E(spl) gene complex.

The Enhancer of split [E(spl)] gene complex belongs to the class of neurogenic loci, which, in a concerted action, govern neurogenesis in Drosophila. Two genetically distinct functions, vital and neurogenic, reside within the complex defined by lethal mutations in the l(3) gro gene and by the typical neurogenic phenotype of deletions, respectively. Such deletions always affect several of the many embryonically active genes in the region, which cannot be mutated separately to lethality. Seven of these genes are extremely similar at the transcription and sequence level sharing the basic helix-loop-helix (bHLH) motif of transcriptional regulators. While these E(spl) bHLH genes seem to be required collectively for neurogenesis, they are nonessential individually, suggesting functional redundancy of the encoded gene products. No specific functions could yet be ascribed to any of the other genes located within the complex. One might expect these apparently dispensable genes, as well as the supposedly redundant bHLH genes, to be under little evolutionary constraint and, thus, to evolve most rapidly. However, we find the entire E(spl) gene complex highly conserved during Drosophila evolution, indicating that all the genes as well as their organization are of functional importance.

Amino Acid Sequence↗
PubMed2006

Regulatory mechanisms of ROI generation are affected by rice spl mutations.

Reactive oxygen intermediates (ROIs) play a pivotal role in the hypersensitive response (HR) in disease resistance. NADPH oxidase is a major source of ROI; however, the mechanisms of its regulation are unclear. Rice spl mutants spontaneously form lesions which resemble those occurring during the HR, suggesting that the mutations affect regulation of the HR. We found that spl2, spl7 and spl11 mutant cells accumulated increased amounts of H(2)O(2) in response to rice blast fungal elicitor. Increased accumulation of ROIs was suppressed by inhibition of NADPH oxidase in the spl cells, and was also observed in the ozone-exposed spl plants. These mutants have sufficient activities of ROI-scavenging enzymes compared with the wild type. In addition, spl7 mutant cells accumulated higher amounts of H(2)O(2) when treated with calyculin A (CA), an inhibitor of protein phosphatase. Furthermore, spl2 mutant plants exhibited accelerated accumulation of H(2)O(2) and increased rates of cell death in response to wounding. These results suggest that the spl2, spl7 and spl11 mutants are defective in the regulation of NADPH oxidase, and the spl7 mutation may give rise to enhancement of the signaling pathway which protein dephosphorylation controls, while the spl2 mutation affects both the pathogen-induced and wound-induced signaling pathways.

Cell Death↗
PubMed1981

The effect of occluded ear impedances on the eardrum SPL produced by hearing aids.

The purpose of the investigation was to determine the effect of eardrum and earmold impedance on eardrum sound pressure level (SPL) produced by a hearing aid receiver. Acoustic interactions between receivers and ears occurring at receiver resonances were explored and analyzed. Results with ear simulators showed that the effect of simulator eardrum impedance was increased in regions where ear and receiver impedance approached each other during resonances. Earmold acoustics were also significant factors at frequencies where their impedance were comparable to ear impedances. Resonant frequency shifts of 540 Hz in the region between 800 and 1500 Hz were observed for the range of simulator eardrum and earmold impedances employed, with SPL changes of 10 dB occurring at some frequencies. Results were different for each of the five receivers tested confirming the effect of the receiver characteristics on the eardrum SPL. A subsequent test was performed using real ears with results that agreed substantially with those obtained with the simulators.

Acoustics↗
PubMed1999

Notchspl is deficient for inductive processes in the eye, and E(spl)D enhances split by interfering with proneural activity.

Eye development in Drosophila involves the Notch signaling pathway at several consecutive steps. At first, Notch signaling is required for stable expression of the proneural gene atonal (ato), thereby maintaining neural potential of the cells. Second, in a process of lateral inhibition, Notch signaling is necessary to confine neural commitment to individual photoreceptor founder cells. Later on, the successive addition of cells to maturing ommatidia is under Notch control. In contrast to previous assumptions, the recessive Notch allele split (Nspl) involves specifically loss of the early proneural Notch activity in the eye, which is in agreement with bristle defects as well. As a result, fewer cells gain neural potential and fewer ommatidia are founded. Enhancement of this phenotype by the dominant mutation Enhancer of split [E(spl)D] happens within the remaining proneural cells, in which Ato expression is abolished. In line with genetic data, this process occurs primarily at the protein level due to altered protein-protein interactions between the aberrant E(spl)D and proneural proteins. Nspl is the first Notch mutation known to specifically affect Notch inductive processes during eye development.

Alleles↗