摘要:

This research investigates the human observer's ability to discriminate difference in duration for noise bursts and gated sinusoids. Two observers compared two durationsTandT+ΔTin a two‐alternative forced‐choice procedure. The value ofTranged from 0.16 to 960 msec. For eachTthe value of ΔTfor 75% discrimination was determined. The results showed that for most of the range investigated ΔTwas proportional toT12. Performance was not affected by a change in bandwidth from 3500 to 200 Hz. Values of ΔTfor 75% correct did decrease, however, when the observers were given audible spectral cues from very short pulsed sinusoids. The theory best describing the results was the neural counter model proposed by Creelman [J. Acoust. Soc. Amer.34, 582–593 (1962)].

ISSN:0001-4966    

DOI:10.1121/1.1912963

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

A speaker recorded lists of words on video tape. These lists were presented to normally hearing children and adults and to profoundly deaf children (average hearing threshold level greater than 95 dB ISO) for recognition through visual or combined acoustic‐visual (A‐V) modalities. For the normals, the acoustic stimulus was a 500‐Hz octave‐band noise amplitude‐modulated by the envelope of the speech signal. For the profoundly deaf observers, the acoustic signal was either modulated noise or linearly amplified speech. Regardless of the type of acoustic signal they received, the mean A‐V scores of the deaf children were 7% to 11% higher than their mean visual scores. The normals also demonstrated small mean improvements (6% to 8%) over visual reception when allowed both to watch the speaker's face and to listen to modulated noise. These results suggest that profoundly deaf children perceive mainly time‐intensity (envelope) information when they are provided with an amplified speech signal.

ISSN:0001-4966    

DOI:10.1121/1.1912964

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Binaural frequency difference limens in noise were obtained under homophasic and antiphasic conditions. Signal frequencies of 200, 300, 500, 700, and 1000 Hz were investigated at 5‐ and 10‐dB sensation levels while 500 Hz was also explored at 15, 20, and 25 dB. The masker was a bandlimited noise with a spectrum level of 55 dB. Results indicate significant changes in discrimination behavior as a function of phase condition and sensation level. Alternative interpretations of the data are considered.

ISSN:0001-4966    

DOI:10.1121/1.1912965

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

The influence of the rise time on the loudness of sound pulses and the meaning of the sound spectrum on this influence were examined. A “paired comparison” method was used. The sound pulses had a duration of 0.7 to 1.0 sec and the rise time was varied between 0.03 and 1.0 sec. For most of the measurements, a signal level of 95 dBre2×10−5N/m2was used. The signals with the fastest onset showed the highest loudness. The influence of the rise time on the loudness was significantly dependent on the signal spectrum. The possibility of explaining the observed effects on the basis of changed synchronism of the neural activity and on the basis of a rapid adaptation in the nervous system is discussed.

ISSN:0001-4966    

DOI:10.1121/1.1912966

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Five male students (19 20 years old) with normal ears were given exposures to (1) steady‐state noise, (2) vibration, and (3) noise and vibration at the same time. In a control experiment the subject sat beside the moving vibrator with ear plugs and earmuffs. Temporary threshold shift (TTS) occurred after both 20 and 60 min of exposure to the vibration of acceleration 500 cm/sec2and frequency 5 Hz, which is regarded as a resonance frequency of human body. The TTS by a steady‐state noise [101‐dB sound‐pressure level (SPL) broad band] was increased by simultaneous vibration (500 cm/sec2and 5 Hz).

ISSN:0001-4966    

DOI:10.1121/1.1912967

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

The purpose of this experiment was to clarify the effects of exposure to intermittent and continuous rock and roll music on hearing threshold level. Twenty normal‐hearing females were exposed to recorded rock and roll music on two occasions in a sound field at 110‐dB sound‐pressure level. One taped recording consisted of music played continuously for 60 min; the other recording was the same music, but with 1 min of discotheque ambient noise (“break times”) spliced between each 3‐min musical selection. Pure‐tone air‐conduction threshold levels were measured monaurally via Békésy audiometry at 1000, 2000, 3000, 4000, 6000, and 8000 Hz prior to, and four times following, each exposure. Temporary threshold shift (TTS) and recovery patterns from the continuous and intermittent conditions were compared. Statistical analysis revealed that TTS2in the intermittent condition was significantly less than in the continuous condition at 2000, 3000, 4000, and 8000 Hz. Recovery time, however, was similar under both conditions.

ISSN:0001-4966    

DOI:10.1121/1.1912968

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

The effectiveness of electrical stimulation of the crossed olivocochlear bundle (COCB) was measured at different locations along the cochlear partition. Differential electrodes were used to sample the cochlear microphonic (CM) at turns I, II, and III. A pipette inserted into scala media in turns I, II, and III was used to measure the slow negative potential associated with electrical stimulation of the COCB. The responses of auditory nerve fibers were sampled within the modiolus and included a wide range of best frequencies. The magnitude of the slow negative potential was maximum in turn I and decreased in turns II and III. The increment in CM, produced by COCB stimulation, depended not only upon the location along the cochlear partition from which it was recorded, but also upon acoustic frequency. For low‐frequency acoustic signals (below 700 Hz), the increment in CM was greatest at turn I and decreased toward the apex. At 5 kHz, COCB stimulation produced no detectable increment in CM at turn I. The reduction in discharges of auditory nerve fibers produced by COCB stimulation was greatest (16–20 dB in titration) when best frequency lay between 7 and 10 kHz. As best frequency decreased, the reduction in discharge rate with COCB stimulation decreased. Nerve fibers with very high best frequencies also showed minimal COCB effects. These data are discussed in relation to other recent information.

ISSN:0001-4966    

DOI:10.1121/1.1912969

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

It has been shown repeatedly that Weber's law does not hold for intensity discrimination of pulsed tones. The masking function for such waveforms (10 logΔIvs 10 logI, for constant performance) typically is linear with a slope of 0.9 over a range inIof at least 60 dB. The present experiment indicates that the slope of the masking function increases from 0.9 to 1.0 as regions above the signal frequency are masked by filtered noise. A sufficient condition for a slope of 1.0 is a high‐pass noise which masks regions at and above the second harmonic of the signal. This suggests that the “near miss” to Weber's law reflects the observer's use of information at aural harmonics. A model based upon this notion gives a good quantitative account of the data. The amount of distortion assumed in the model is in reasonable agreement with other data.

ISSN:0001-4966    

DOI:10.1121/1.1912970

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

A threshold‐tracking method was used to measure both the incremental and the decremental just noticeable differences for segment duration in naturally spoken sentences. The measurements were made for a /p/ in five different contexts, including two that were word initial, two that were word medial, and one that was word final; for /∫,m/, and /l/ all in initial prestress position; and for a stressed vowel /ɔ/. The results show that subjects are much more sensitive to changes in vowel duration than to changes in consonant duration, and that changes in segment duration may have several different perceptual effects, including changes in perceived stress and perceived rhythm. When subjects based their judgments on changes in perceived stress or rhythm, they were usually able to detect smaller changes in duration than when they attended to other aspects of the stimuli.

ISSN:0001-4966    

DOI:10.1121/1.1912971

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Experiments were performed to test whether a change made in the duration of one segment in a naturally produced sentence should be compensated in an adjacent segment if the sentence is to remain temporally fluent. The results showed that compensation is required between some pairs of segments, but not between other pairs, depending on where the two segments occur with respect to word and syllable boundaries. The results suggest that the perception of timing in natural speech is based on events at the syllabic level rather than at the segmental level, and that it is important to maintain the rhythm of the sentence, as defined by the onsets of vowels (especially stressed vowels), if the sentence is to sound temporally fluent.

ISSN:0001-4966    

DOI:10.1121/1.1912972

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP