Autocorrelation factors and intelligibility of Japanese monosyllables in individuals with sensorineural hearing loss.

Some Japanese monosyllables contain consonants that are not easily discernible for individuals with sensorineural hearing loss. However, the acoustic features that make these monosyllables difficult to discern have not been clearly identified. Here, this study used the autocorrelation function (ACF), which can capture temporal features of signals, to clarify the factors influencing speech intelligibility. For each monosyllable, five factors extracted from the ACF [Φ(0): total energy; τ1 and ϕ1: delay time and amplitude of the maximum peak; τe: effective duration; Wϕ(0): spectral centroid], voice onset time, speech intelligibility index, and loudness level were compared with the percentage of correctly perceived articulations (144 ears) obtained by 50 Japanese vowel and consonant-vowel monosyllables produced by one female speaker. Results showed that median effective duration [(τe)med] was strongly correlated with the percentage of correctly perceived articulations of the consonants (r = 0.87, p < 0.01). (τe)med values were computed by running ACFs with the time lag at which the magnitude of the logarithmic-ACF envelope had decayed to -10 dB. Effective duration is a measure of temporal pattern persistence, i.e., the duration over which the waveform maintains a stable pattern. The authors postulate that low recognition ability is related to degraded perception of temporal fluctuation patterns.

The Effect of Peripheral Compression on Syllable Perception Measured with a Hearing Impairment Simulator.

Hearing impaired (HI) people often have difficulty understanding speech in multi-speaker or noisy environments. With HI listeners, however, it is often difficult to specify which stage, or stages, of auditory processing are responsible for the deficit. There might also be cognitive problems associated with age. In this paper, a HI simulator, based on the dynamic, compressive gammachirp (dcGC) filterbank, was used to measure the effect of a loss of compression on syllable recognition. The HI simulator can counteract the cochlear compression in normal hearing (NH) listeners and, thereby, isolate the deficit associated with a loss of compression in speech perception. Listeners were required to identify the second syllable in a three-syllable "nonsense word", and between trials, the relative level of the second syllable was varied, or the level of the entire sequence was varied. The difference between the Speech Reception Threshold (SRT) in these two conditions reveals the effect of compression on speech perception. The HI simulator adjusted a NH listener's compression to that of the "average 80-year old" with either normal compression or complete loss of compression. A reference condition was included where the HI simulator applied a simple 30-dB reduction in stimulus level. The results show that the loss of compression has its largest effect on recognition when the second syllable is attenuated relative to the first and third syllables. This is probably because the internal level of the second syllable is attenuated proportionately more when there is a loss of compression.

Pitch perception for sequences of impulse responses whose scaling alternates at every cycle.

The purpose of this study is to investigate the sufficient "similarity" between consecutive auditory events for the auditory system to define the fundamental period for pitch perception. It is possible to contaminate the periodicity of harmonic complex tones by scaling the impulse response in the time domain at every other cycle. Scale-alternating wavelet sequences (SAWS) in which two impulse responses with different scaling factors alternated were generated based on impulse responses obtained from Japanese vowels spoken by a male speaker. Preliminary listening to such signals indicated that the perceived pitch went down an octave relative to the original when the scaling factor exceeded a certain degree. In the first experiment, pitch matching was measured as a function of the scaling factor by the method of adjustment where the comparison stimuli were completely periodic with adjustable base periods. The pitch shift was discontinuous against the base period, chromatic continuum. In the second experiment, pitch matching was investigated with comparison stimuli whose odd harmonics were attenuated. This procedure provides a stimulus continuum where the pitch moved up an octave without changing its pitch chroma. The attenuation of the odd harmonics needed to match the SAWS varied systematically as a function of the degree of scaling. The relation between pitch matching and the peak height along the time interval axis of the stabilized auditory image is discussed.

Transcriptional induction of mammalian ER quality control proteins is mediated by single or combined action of ATF6alpha and XBP1.

Metazoans express three unfolded protein response transducers (IRE1, PERK, and ATF6) ubiquitously to cope with endoplasmic reticulum (ER) stress. ATF6 is an ER membrane-bound transcription factor activated by ER stress-induced proteolysis and has been duplicated in mammals. Here, we generated ATF6alpha- and ATF6beta-knockout mice, which developed normally, and then found that their double knockout caused embryonic lethality. Analysis of mouse embryonic fibroblasts (MEFs) deficient in ATF6alpha or ATF6beta revealed that ATF6alpha is solely responsible for transcriptional induction of ER chaperones and that ATF6alpha heterodimerizes with XBP1 for the induction of ER-associated degradation components. ATF6alpha(-/-) MEFs are sensitive to ER stress. Unaltered responses observed in ATF6beta(-/-) MEFs indicate that ATF6beta is not a negative regulator of ATF6alpha. These results demonstrate that ATF6alpha functions as a critical regulator of ER quality control proteins in mammalian cells, in marked contrast to worm and fly cells in which IRE1 is responsible.

Spontaneous motor tempo contributes to preferred music tempo regardless of music familiarity.

Music, and listening to music, has occurred throughout human history. However, it remains unclear why people prefer some types of music over others. To understand why we listen to a certain music, previous studies have focused on preferred tempo. These studies have reported that music components (external), as well as participants' spontaneous motor tempo (SMT; internal), determine tempo preference. In addition, individual familiarity with a piece of music has been suggested to affect the impact of its components on tempo preference. However, the relationships among participants' SMT, music components, and music familiarity as well as the influence of these variables on tempo preference have not been investigated. Moreover, the music components that contribute to tempo preference and their dependence on familiarity remain unclear. Here, we investigate how SMT, music components, and music familiarity simultaneously regulate tempo preference as well as which music components interact with familiarity to contribute to tempo preference. A total of 23 participants adjusted the tempo of music pieces according to their preferences and rated the familiarity of the music. In addition, they engaged in finger tapping at their preferred tempo. Music components, such as the original tempo and the number of notes, were also analyzed. Analysis of the collected data with a linear mixed model showed that the preferred tapping tempo of participants contributed to the preferred music tempo, regardless of music familiarity. In contrast, the contributions of music components differed depending on familiarity. These results suggested that tempo preference could be affected by both movement and memory.

A time-dependent phase shift in the mammalian unfolded protein response.

Unfolded or misfolded proteins in the endoplasmic reticulum (ER) must be refolded or degraded to maintain homeostasis of the ER. The ATF6 and IRE1-XBP1 pathways are important for the refolding process in mammalian cells; activation of these transcriptional programs culminates in induction of ER-localized molecular chaperones and folding enzymes. We show here that degradation of misfolded glycoprotein substrates requires transcriptional induction of EDEM (ER degradation-enhancing alpha-mannosidase-like protein), and that this is mediated specifically by IRE1-XBP1 and not by ATF6. As XBP1 is produced after ATF6 activation, our results reveal a time-dependent transition in the mammalian unfolded protein response: an ATF6-mediated unidirectional phase (refolding only) is followed by an XBP1-mediated bidirectional phase (refolding plus degradation) as the response progresses.

Music Memory Following Short-term Practice and Its Relationship with the Sight-reading Abilities of Professional Pianists.

This study investigated the relationship between the ability to sight-read and the ability to memorize a score using a behavioral experiment. By measuring the amount of memorization following short-term practice, we examined whether better sight-readers not only estimate forthcoming notes but also memorize musical structures and phrases with more practice. Eleven pianists performed the music first by sight-reading. After a 20-minute practice, the participants were asked to perform from memory without any advance notice. The number of mistakes was used as an index of performance. There were no correlations in the numbers of mistakes between sight-reading and memory trial performance. Some pianists memorized almost the entire score, while others hardly remembered it despite demonstrating almost completely accurate performance just before memory trial performance. However, judging from the participants' responses to a questionnaire regarding their practice strategies, we found auditory memory was helpful for memorizing music following short-term practice.

Cartilage conduction efficiently generates airborne sound in the ear canal.

OBJECTIVE: By attaching a transducer to the aural cartilage, a relatively loud sound is audible even with a negligibly small fixation force. Previous study has identified several pathways for sound transmission by means of cartilage conduction. This investigation focused on the relative contribution of direct vibration of the aural cartilage to sound transmission in an open and in an occluded ear. METHODS: Thresholds with and without an earplug were compared for three experimental conditions: the transducer being placed on the tragus, pretragus, and mastoid. Eight volunteers with normal hearing participated. RESULTS: The thresholds increased with distance of the transducer from the ear canal (tragus, pretragus, mastoid, in that order). The differences were statistically significant for all conditions except for the occluded ear at 4 kHz. With the earplug inserted, the thresholds for the tragus condition were most sensitive below 2 kHz, indicating a significant contribution of direct vibration of the aural cartilage. CONCLUSION: Direct vibration of the aural cartilage can enhance sound transmission. At low frequencies, cartilage conduction can deliver sound efficiently across a blockage in the ear canal. Stray airborne sound radiating from the transducer dominates cartilage conduction in the open ear at high frequencies.

Evaluation of speech intelligibility in short-reverberant sound fields.

OBJECTIVE: The purpose of this study was to explore the differences in speech intelligibility in short-reverberant sound fields using deteriorated monosyllables. Generated using digital signal processing, deteriorated monosyllables can lack the redundancy of words, and thus may emphasize differences in sound fields in terms of speech clarity. METHODS: Ten participants without any hearing disorders identified 100 monosyllables convolved with eight impulse responses measured in different short-reverberant sound fields (speech transmission index >0.6 and reverberation time <1s), and we compared speech recognition scores between normal and deteriorated monosyllables. Deterioration was produced using low-pass filtering (cut off frequency=1600Hz). RESULTS: Speech recognition scores associated with the deteriorated monosyllables were lower than those for the normal monosyllables. In addition, scores were more varied among the different sound fields, although this result was not significant according to an analysis of variance. In contrast, the variation among sound fields was significant for the normal monosyllables. When comparing the intelligibility scores to the acoustic parameters calculated from eight impulse responses, the speech recognition scores were the highest when the reverberant/direct sound energy ratio (R/D) was balanced. CONCLUSIONS: Although our deterioration procedure obscured differences in intelligibility score among the different sound fields, we have established that the R/D is a useful parameter for evaluating speech intelligibility in short-reverberant sound fields.

Is cartilage conduction classified into air or bone conduction?

OBJECTIVES/HYPOTHESIS: The aim of this study was to establish the sound transmission characteristics of cartilage conduction proposed by Hosoi (2004), which is available by a vibration signal delivered to the aural cartilage from a transducer. STUDY DESIGN: Experimental study. METHOD: Eight volunteers with normal hearing participated. Thresholds at frequencies of 0.5, 1, 2, and 4 kHz for air conduction, bone, and cartilage conductions were measured with and without an earplug. The sound pressure levels on the eardrum at the threshold estimated with a Head and Torso Simulator were compared between air and cartilage conductions. The force levels calibrated with an artificial mastoid at the threshold were compared between bone and cartilage conductions. RESULTS: The difference in the estimated sound pressure levels on the eardrum at the thresholds between air and cartilage conductions were within 10 dB. In contrast, the force levels at the thresholds for cartilage conduction were remarkably lower than those for bone conduction. These findings suggested that sounds were probably transmitted via the eardrum for cartilage conduction. The threshold shifts by an earplug showed no significant difference between bone and cartilage conductions at 0.5 kHz. At 1 and 2 kHz, the threshold-shifts increased significantly in the order of bone, cartilage, and air conductions. These results suggested that airborne sound induced by the vibration of the cartilaginous portion of the ear canal played a significant role in sound transmission for cartilage conduction. CONCLUSIONS: Cartilage conduction has different characteristics from conventional air and bone conductions.

Activation of the left superior temporal gyrus of musicians by music-derived sounds.

Previous studies have suggested that professional musicians comprehend features of music-derived sound even if the sound sequence lacks the traditional temporal structure of music. We tested this hypothesis through behavioral and functional brain imaging experiments. Musicians were better than nonmusicians at identifying scrambled pieces of piano music in which the original temporal structure had been destroyed. Bilateral superior temporal gyri (STG) activity was observed while musicians listened to the scrambled stimuli, whereas this activity was present only in the right STG of nonmusicians under the same experimental conditions. We suggest that left STG activation is related to the processing of deviants, which appears to be enhanced in musicians. This may be because of the superior knowledge of musical temporal structure held by this population.

Benefit of a new hearing device utilizing cartilage conduction.

OBJECTIVE: Our previous study demonstrated that sound was effectively transmitted by attaching a transducer to the aural cartilage even without fixation pressure. This new method for sound transmission was found by Hosoi in 2004, and was termed cartilage conduction (CC). CC can be utilized even in hearing-impaired patients who cannot use air-conduction hearing aids owing to continuous otorrhea or aural atresia. A prototype hearing aid employing CC was investigated in this study. METHODS: Four patients with conditions such as continuous otorrhea and acquired aural atresia after surgery participated in this study. The CC hearing aid was fitted, and its benefits were assessed by audiometric tests and interview. RESULTS: Thresholds and speech recognition scores improved in all subjects. However, in subjects with continuous otorrhea, it was difficult to obtain the gains according to the target gains owing to their severe hearing loss and the limitation of the output level. On the other hand, unexpectedly large gains were obtained below 2kHz in the patient with acquired aural atresia. These large gains were probably caused by soft tissue filling the postoperative space. No subjects complained of pain associated with the attachment of the transducer, although such problems are usually observed for a bone-conduction (BC) hearing aid. This feature is considered one of the advantages of the CC hearing aid. CONCLUSION: The results of the audiometric tests and interview suggest that the CC hearing aid has potential as a useful amplification device for hearing disability. Unfortunately, if the soft tissue pathway is not involved, the current device is insufficient for the patients with severe hearing loss. The improvement of the output level will lead to develop a reliable CC hearing aid as an alternative to BC hearing aids or bone anchored hearing aids.

The cargo receptor ERGIC-53 is a target of the unfolded protein response.

The accumulation of unfolded proteins in the ER triggers a signaling response known as unfolded protein response (UPR). In yeast the UPR affects several hundred genes that encode ER chaperones and proteins operating at later stages of secretion. In mammalian cells the UPR appears to be more limited to chaperones of the ER and genes assumed to be important after cell recovery from ER stress that are not important for secretion. Here, we report that the mRNA of lectin ERGIC-53, a cargo receptor for the transport of glycoproteins from ER to ERGIC, and of its related protein VIP36 is induced by the known inducers of ER stress, tunicamycin and thapsigargin. In parallel, the rate of synthesis of the ERGIC-53 protein was induced by these agents. The response was due to the UPR since it was also triggered by castanospermine, a specific inducer of UPR, and inhibited by genistein. Thapsigargin-induced upregulation of ERGIC-53 could be fully accounted for by the ATF6 pathway of UPR. The results suggest that in mammalian cells the UPR also affects traffic from and beyond the ER.