Ofer Amir

Pitch discrimination: are professional musicians better than non-musicians?

Musicians are typically considered to exhibit exceptional auditory skills. Only few studies, however, have substantiated this in basic psychoacoustic tasks. The purpose of the present investigation was to expand our knowledge on basic auditory abilities of musicians compared to non-musicians. Specific goals were: (1) to compare frequency discrimination thresholds (difference limen for frequency [DLF]) of non-musical pure tones in controlled groups of professional musicians and non-musicians; (2) to relate DLF performance to musical background; and (3) to compare DLF thresholds obtained with two threshold estimation procedures: 2- and 3- interval forced choice procedures (2IFC and 3IFC). Subjects were 16 professional musicians and 14 non-musicians. DLFs were obtained for three frequencies (0.25, 1 and 1.5 kHz) using the 3IFC adaptive procedure, and for one frequency (1 kHz) also using the 2IFC. Three threshold estimates were obtained for each frequency, procedure and subject. The results of the present study support five major findings: (a) mean DLFs for musicians were approximately half the values of the non-musicians; (b) significant learning for both groups during the three threshold estimations; (c) classical musicians performed better than those with contemporary musical background; (d) performance was influenced by years of musical experience; and (e) both groups showed better DLF in a 2IFC paradigm compared to the 3IFC. These data highlight the importance of short-term training on an auditory task, auditory memory and factors related to musical background (such as musical genre and years of experience) on auditory performance.

The impact of hormonal fluctuations on female vocal folds.

Purpose of reviewSex hormone fluctuations were shown to affect female vocal folds and laryngeal function. Laryngeal changes are evident throughout the span of life, starting at puberty with the arousal of the hormonal system, fluctuating systematically during the reproductive years with the menstrual cycle, and then changing again with the decline of hormonal activity at menopause. This paper reviews recent developments in this field. Recent findingsEarly studies that explored this relation were based merely on subjective impressions of voice quality, recent studies have used more objective tools for examining this relation, including histologic observations, stroboscope, electroglottography (EGG), and computerized acoustic analyses. In these studies, the larynx was shown to be a hormonal target organ and, as such, sex hormones affect its morphology, histology, and function, similar to their effect on the genitals and other organs. SummaryExamining the relation between sex hormones and the larynx could assist in understanding the mechanisms of voice production, and it could provide the clinician with supplemental diagnostic information on different medical conditions.

The frontal aslant tract underlies speech fluency in persistent developmental stuttering.

The frontal aslant tract (FAT) is a pathway that connects the inferior frontal gyrus with the supplementary motor area (SMA) and pre-SMA. The FAT was recently identified and introduced as part of a “motor stream” that plays an important role in speech production. In this study, we use diffusion imaging to examine the hypothesis that the FAT underlies speech fluency, by studying its properties in individuals with persistent developmental stuttering, a speech disorder that disrupts the production of fluent speech. We use tractography to quantify the volume and diffusion properties of the FAT in a group of adults who stutter (AWS) and fluent controls. Additionally, we use tractography to extract these measures from the corticospinal tract (CST), a well-known component of the motor system. We compute diffusion measures in multiple points along the tracts, and examine the correlation between these diffusion measures and behavioral measures of speech fluency. Our data show increased mean diffusivity in bilateral FAT of AWS compared with controls. In addition, the results show regions within the left FAT and the left CST where diffusivity values are increased in AWS compared with controls. Last, we report that in AWS, diffusivity values measured within sub-regions of the left FAT negatively correlate with speech fluency. Our findings are the first to relate the FAT with fluent speech production in stuttering, thus adding to the current knowledge of the functional role that this tract plays in speech production and to the literature of the etiology of persistent developmental stuttering.

The Hebrew Vowel System: Raw and Normalized Acoustic Data

It is well known that different languages use different vowel systems interms of variety and number. The Hebrew vowel system consists of five vowels /i, e, a, o, u/. The present research identified the acoustic features of the vowels produced by Hebrew speakers differing in age and sex. Ninety speakers (men, women, boys, and girls) were recorded. The vowels were presented in a nonword context that was placed in a meaningful Hebrew sentence. The data included measurements of F0, F1, F2, F3, F4, and vowel duration for the five different vowels produced by the four groups of participants. Conversion of the physical frequency measures of formants into a critical band (bark) scale was performed as well. The results indicated that the F2/F1 ratio is a distinctive feature of all five vowels, keeping with the findings of previous research in other languages. Nevertheless, the values of the F2/F1 ratios led to an overlap between different vowels producedby different groups of speakers. Applying the bark transformation as speaker normalization procedure succeeded in reducing speaker differences while increasing vowel differences.

The Effect of Oral Contraceptives on Voice: Preliminary Observations

Most studies investigating the effect of sex hormones on the larynx and vocal folds focused on the voice quality of women either around menopause or during the menstrual cycle. To our knowledge, however, there have been no studies that investigated the effect of oral contraceptives on the female voice. In the present study five women who ingest oral contraceptives (pill group) and five women who do not (natural group) were recorded producing the vowels /i/ and /a/ repeatedly over a period of 40 days. Acoustic analyses were performed on these recordings including F0, amplitude, jitter, shimmer, and harmonic-to-noise ratio (HNR). Results indicated that jitter and shimmer values of the pill group were significantly lower than those of the natural group. No group differences were found for F0, amplitude, or HNR. In addition, the pill group demonstrated significantly smaller variance for all variables tested. The results suggest that oral contraceptives might increase voice stability associated with smaller hormonal changes. Thus the present study provides preliminary evidence of the effect of oral contraceptives on the female voice.

Do Women's Voices Provide Cues of the Likelihood of Ovulation? The Importance of Sampling Regime

The human voice provides a rich source of information about individual attributes such as body size, developmental stability and emotional state. Moreover, there is evidence that female voice characteristics change across the menstrual cycle. A previous study reported that women speak with higher fundamental frequency (F0) in the high-fertility compared to the low-fertility phase. To gain further insights into the mechanisms underlying this variation in perceived attractiveness and the relationship between vocal quality and the timing of ovulation, we combined hormone measurements and acoustic analyses, to characterize voice changes on a day-to-day basis throughout the menstrual cycle. Voice characteristics were measured from free speech as well as sustained vowels. In addition, we asked men to rate vocal attractiveness from selected samples. The free speech samples revealed marginally significant variation in F0 with an increase prior to and a distinct drop during ovulation. Overall variation throughout the cycle, however, precluded unequivocal identification of the period with the highest conception risk. The analysis of vowel samples revealed a significant increase in degree of unvoiceness and noise-to-harmonic ratio during menstruation, possibly related to an increase in tissue water content. Neither estrogen nor progestogen levels predicted the observed changes in acoustic characteristics. The perceptual experiments revealed a preference by males for voice samples recorded during the pre-ovulatory period compared to other periods in the cycle. While overall we confirm earlier findings in that women speak with a higher and more variable fundamental frequency just prior to ovulation, the present study highlights the importance of taking the full range of variation into account before drawing conclusions about the value of these cues for the detection of ovulation.

Evaluating the validity of the Voice Handicap Index-10 (VHI-10) among Hebrew speakers.

OBJECTIVE: To evaluate the validity of a translated version of the Voice Handicap Index-10 (VHI-10). STUDY DESIGN AND SETTING: In a parallel group design, 221 patients with different laryngeal pathologies and 172 people with no laryngeal pathology completed a Hebrew version of the VHI-10. Validity and reliability were assessed as well as group differences. RESULTS: Statistical analyses demonstrated high reliability values (Cronbachs Alpha r = 0.949). Responses were not affected by age (P = 0.373) or gender (P = 0.360). The control group received significantly lower scores than all pathological groups (P < 0.05). Within the pathological groups, the “neurogenic” and “mucosa irregularity’ groups were rated higher than all other pathological groups (P < 0.05). CONCLUSION: The VHI-10 questionnaire maintains its validity and reliability across translation to Hebrew. Moreover, although the VHI-10 is essentially a unidimensional tool, it provides partial information on the 3 subjective dimensions of the full VHI.

Association Between Birth Control Pills and Voice Quality

Objectives/Hypothesis: The objective was to extend our knowledge of the effect of birth control pills on voice quality in women based on various acoustic measures.

Do oral contraceptives improve vocal quality? Limited trial on low-dose formulations

OBJECTIVE To evaluate the effect of low-dose monophasic oral contraceptives on female vocal quality. METHODS Acoustic voice parameters of six women who use oral contraceptives and six women who do not were evaluated repeatedly during the menstrual cycle. Frequency and amplitude variations were measured using a computerized voice analysis program. Repeated-measures analysis of variance was performed to test differences between groups for each acoustic voice parameter. RESULTS Vocal stability among the women who use oral contraceptives was significantly better than among those who did not use oral contraceptives (P < .05). Specifically, amplitude and frequency variations between successive vocal cycles were smaller in women using oral contraceptives in comparison with the control group (.24 dB versus .37 dB and .86% versus 1.27% for amplitude and frequency variations, respectively). CONCLUSION Contrary to the reports of adverse effects that high-dose pills have on voice, low-dose oral contraceptives show a favorable influence on voice in young women.

The effect of training on frequency discrimination: generalization to untrained frequencies and to the untrained ear.

While there is growing evidence that frequency discrimination improves with practice, there are, however, limited and inclusive reports regarding the generalization of learning to untrained conditions. The goals of the present study were therefore (1) to measure the effect of multi-session training on difference limen frequency (DLF) thresholds and evaluate the relative contribution of procedural and stimulus learning by comparison to a control (untrained) group; (2) to evaluate the extent of generalization of the trained frequency to two untrained frequencies known to be temporally coded; and (3) to estimate the generalization of the trained frequency to the untrained ear, for both trained and untrained frequencies. Two groups of subjects were included: a trained group (n = 5) and a control group (n = 5). For the trained group, DLF thresholds for 1 kHz (trained frequency) and 1.1 and 2.0 kHz (untrained frequencies) were obtained using a two-interval, two-alternative forced choice paradigm before and after an eight-session training. The control group was tested using the same stimuli only twice, with a 3-week interval between testing. Results showed that (1) multi-session training improves frequency discrimination in normal hearing young adults; (2) adding a control group to the study allowed estimation of the effect of limited exposure to the stimuli and task in naïve listeners and evaluation of the magnitude of procedural learning; (3) learning was generalized across frequencies that are coded by similar mechanisms; (4) generalization of learning occurred in the untrained ear for trained and untrained frequencies. These results have important clinical and theoretical implications regarding the processes underlying perceptual learning and the effectiveness of auditory habilitation strategies.