摘要:

Combining correlative analysis of acoustic musical instrument sounds with basic physical properties leads to functional models for electronic synthesis. Determination of the number of degrees of freedom and their ranges associated with psychoacoustically important parameters is crucial for efficient models. Derivation of three models for the trumpet, violin, and French horn and simulative synthesis examples will be presented.

ISSN:0001-4966    

DOI:10.1121/1.2015473

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP

摘要:

Working techniques and philosophy for our particular approach in producing electronic music recordings will be discussed. The studio facility will be discussed, particularly its unique features. An example of a typical complex musical passage will be played in component and find forms. We also will attempt to cover several mixing situations in which both quad and stereo “imaging” may be made to simulate that of a natural acoustic environment.

ISSN:0001-4966    

DOI:10.1121/1.2015549

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP

摘要:

Blood alcohol levels between 0.09% and 0.15% were found to reduce the protective action of the acoustic reflex in five normal hearing human subjects. Specifically, acoustic reflex thresholds were raised, reflex magnitude decreased, and TTS increased under alcohol conditions. Stimuli consisted of a narrowband noise (500–1000 Hz) and a 500‐Hz pure tone. Measurements were made at blood alcohol concentrations from 0.05% to 0.15%. TTS at 1000 Hz was determined three minutes following a 10‐min exposure of narrowband noise at −5, +5, and +20 dB relative to the subject's pre‐alcohol acoustic reflex threshold. [Work supported by NIH.]

ISSN:0001-4966    

DOI:10.1121/1.2015661

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP

摘要:

A body of anatomical, electrophysiological, psychophysical, and behavioral research supports the proposition that there is a division in audition similar to the rod/cone dichotomy in vision. Evidence will be presented for the presence of discrete processes for low and high intensity sounds. Both can be identified in electrophysiological measurements at all levels of the auditory nervous system. Both processes can also be discerned in magnitude estimates of loudness. If subjective loudness is plotted as a function of the cube root of sound pressure, the curve consists of two linear sections with a discontinuity of slope at approximately 65 dB SPL. Both segments are present for frequencies up to at least 3 kHz. Linearity is preserved in the presence of a masking noise but the variation in slope and intercept constants suggests the operation of different mechanisms of masking for each process.

ISSN:0001-4966    

DOI:10.1121/1.2015743

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP

摘要:

The aim of this paper is to promote a better understanding of hearing impairment as a communicative handicap, primarily in noisy enviornments, and to explain the essentially limited applicability of the hearing aid. From available data we can conclude that about 7.5% of the population is auditory handicapped, with a hearing loss for speech ⩾ 24 dB. Every hearing loss can be interpreted as the sum of a loss class A (Attenuation), characterized by a reduction of the levels of both speech signal and noise, and a loss class D (Distortion), comparable with a decrease in speech‐to‐noise ratio. On the average, the hearing loss of class D (= hearing loss in noise) appears to be about one‐third (in dB) of the total hearing loss (A + D = hearing loss in quiet). A hearing aid can compensate class‐A hearing losses, giving difficulties primarily in quiet, but not class‐D hearing losses, giving difficulties primarily in noise. The latter class represents the first stage of auditory handicap, beginning at an average hearing loss of about 24 dB. An algorithm for computing speech level relative to speech‐reception threshold as a function of hearing losses of classes A and D, as well as acoustic gain, internal noise, and quality of the hearing aid, has been developed and examples will be given.

ISSN:0001-4966    

DOI:10.1121/1.2015802

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP

摘要:

Relative onset times of voicing and visible articulation are potential cues for lipreaders to recognize nasal/stop consonants. For bilabials, a phototransistor behind the teeth and an external microphone indicated mouth opening and voice onset, respectively. Average voice leads for ten adults were: /ma/, +66 msec; /ba/, −1 msec; /pa/, −8 msec (/ma‐ba/ boundary, +28 msec; /ba‐pa/ boundary, −18 msec). To test relative voice/mouth onset as aperceptualcue. we produced synthetic syllables: the face substitute was an oscilloscope pattern, forming a mouth shape for 250, 400. or 550 msec; the voice substitute was a vowel‐like buzz delivered through a hand‐held vibrator. Buzz accompanied mouth opening with lead times of +200 to −200 msec (40 msec steps), and ended simultaneously with mouth closure. Normal‐hearing observers labeled each combination “ma” “ba.” or “pa.” Practiced lipreaders with knowledge of the onset cue subdivided the continuum with boundaries at +82 msec (ma‐ba) and −87 msec (ba‐pa). Because articulatory and perceptual boundaries are not coincident, this combined‐mode cue appears insufficient unless performance can be improved through training.

ISSN:0001-4966    

DOI:10.1121/1.2015856

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP

摘要:

The purpose of this study was to investigate intrusion errors for consonants in short‐term memory (STM) when perceived in varying signal‐to‐noise (S/N) ratio conditions. Stimuli were eighteen English consonants paired with the vowel /a/, and presented in groups of nine blocked in threes. Twenty‐seven phonetically trained college students were separated into three groups of nine subjects each. Subjects in each group heard the stimuli in either (1) 0 dB S/N, (2) −5 dB S/N, or (3) −10 dB S/N ratios (reMCL); transcribed their responses; covered them; and recalled items from STM. A paradigm described earlier [W. Wickelgren, J. Acoust. Soc. Am.39, 388–398 (1966)] was used for stimulus presentation and recording of results. Subjects' error data were submitted to INDSCAL and analyzed for distinctive features. Features were compared across noise conditions and to earlier studies. Data were also analyzed in terms of number correct.

ISSN:0001-4966    

DOI:10.1121/1.2015902

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP

摘要:

Normal children 5–8 years old, were tested on a new speech discrimination procedure. Stimuli were monosyllabic nouns within the receptive vocabularies of three‐year‐old inner‐city children. An up—down procedure tracked the 71% correct level of response. Open‐ and closed‐set conditions were tested. Closed‐set conditions used four‐alternative picture responses. Subjects were tested in quiet with an open response set (no pictures) and then on three closed‐set conditions: quiet, with a 12‐talker‐babble masker at 70 dB SPL, and with a filtered‐noise masker (filtered to have the same spectrum as the babble) at 70 dB SPL. Thresholds in babble were about 10 dB higher than thresholds in noise, and open‐set quiet thresholds were about 10 dB higher than closed‐set quiet thresholds. No age differences were observed. The absence of an age effect with the monosyllable stimulus items contrasts with an earlier report [L. L. Elliott, J. Acoust. Soc. Am.60, S28 A (1976)] where there was an age effect for older children tested in noise on a linguistically more complex task. [Supported by BEH.]

ISSN:0001-4966    

DOI:10.1121/1.2015963

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP

摘要:

OTI has developed and is producing a shipboard signal processor for interfacing noise and vibration sensor signals with a digital computer and narrow‐band spectrum analyzer. The Monitoring System Signal Processor (MSSP) provides for 144 accelerometer and 6 hydrophone inputs, as well as A/D rand D/A conversions of auxiliary dc, ac, and discrete signals. The MSSP scans the input channels and conditions the incoming signals which are then fed through a bandpass filter and selector. The selected band is connected to a variable gain amplifier. The scaled analog data are low‐pass filtered, sampled, and converted to digital format. A block of 2048 digital samples are then stored and block transferred to the computer. The computer transfers the data to a separate spectrum analyzer for narrow‐band frequency conversion and13 octaveband generation. The computer provides for storage of threshold values for various ship speed ranges, and generates alarms and displays for operator action when these limits are exceeded. The system can be reconfigured to incorporate the frequency transform function into the MSSP. In conjunction with a small computer and suitable peripheral equipment this would comprise a compact NVM system for shipboard or industrial applications. [Work supported by NAVSEA and NAVSEC under Contract N00024‐75‐C‐7217.]

ISSN:0001-4966    

DOI:10.1121/1.2016005

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP

摘要:

The dynamical‐mechanical properties of elastomer materials, which are widely used in devices such as antivibration mounts, are known to depend upon the nature of the loading of the material. While many aspects of the dependence of the dynamic properties on frequency and temperature are well known and customarily accounted for, these properties are also known to vary significantly with other aspects of the loading such as strain amplitude and static load. Furthermore, not all of these aspects of the loading appear to act independently. In this paper we discuss the dependence of the dynamic properties of elastomers on frequency, dynamic strain amplitude, and static loading. While the effects of frequency and strain amplitude appear to be separable, it does not appear to be as easy to deal with the effects of static loading. The implications of these effects on designs using elastomers is discussed. [Sponsored by USN Office of Naval Research—Structural Mechanics Program.]

ISSN:0001-4966    

DOI:10.1121/1.2015403

出版商:Acoustical Society of America    

年代:1977

数据来源: AIP