Single Ear Research Articles

Physiological activation of the stapedius muscle in Gallus gallus.

The function of the avian middle ear muscle was investigated in the chicken, Gallus gallus (domesticus). The avian species offers excellent conditions for study of middle ear muscle function since it possesses a single middle ear muscle, the stapedius, which is located extracranially. Electromyograms (EMG), measurements of impedance change, and volume change in the middle ear cavity were used to assess the muscle's activity. The results showed that the middle ear muscle of Gallus does not exhibit an acoustic reflex. However, the stapedius is regularly activated during the animal's own vocalization. Measurements of the EMG and volume change showed the stapedial activity to increase systematically with increases in the vocal sound level. The use of volume change as a measure of stapedius function was found to be highly suitable in the present experiments in that it allows for measurements of the magnitude of the stapedius contraction without altering the intact physiological state of the middle ear, and is insensitive to the ambient noise and vocal sounds, that hamper the impedance technique.

Directed Attention and Perceptual Asymmetry to Monaurally Presented Tones

Forty-eight right-handed Ss were tested for simple reaction time (RT) to a monaurally presented 1000 Hz tone of 250 msec duration. Each S was tested in 3 series comprising 7, 11 and 15 stimulus presentations (trials). In each series all stimuli but one (probe) were presented to a single ear. Ss were divided equally into right or left-ear attention groups on the basis of the ear receiving the non-probe trials. Right-ear attention resulted in equally good RTs to either attended or non-attended ear. Left-ear attention resulted in slower RTs than right-ear attention and showed a significant discrepancy between ears in favor of the non-attended ear. The results are interpreted as showing that neither simulus competition nor language processing are necessary conditions for eliciting auditory asymmetry. The data indicate that a cortically-mediated process of selective attention operates in the production of auditory asymmetries for some non-language sounds and that, as with language perception, it is the left cerebral hemisphere that is primarily involved.

The whalebill is a stork

THE avian order Ciconiiformes contains a heterogeneous assemblage of long legged, long necked birds which have traditionally been classified together because of superficial resemblance. The order usually contains the storks, ibises, herons and two rather aberrant birds, the whalebill (Balaeniceps rex) and the hammerkop (Scopus umbretta), which are placed in monotypic families, the Balaencipitidae and Scopidae, respectively. The evolutionary relationships among the members of the Ciconiiformes and between this order and other living birds are little understood. Using an analysis of the morphology of the stapes (the single avian ear ossicle)1,2, I have obtained evidence for the evolutionary affinity of the whalebill with the storks, which now seem to form a monophyletic assemblage.

The perception of alternated speech

When speech is rapidly alternated between the two ears, intelligibility declines as rates approach 3–5 switching cycles/sec and then paradoxically returns to a good level beyond that point. The present study examines previous explanations of the phenomenon by comparing intelligibility of alternated speech with that for presentation of an interrupted message to a single ear. Results favor one of two possible explanations, and a theoretical model to account for the effect is proposed.

Field trials of insecticides in controlled-release devices for control of the Gulf Coast tick and prevention of screwworm in cattle.

In field trials conducted during July-September 1975, stirofos (15% AI) in both a small-double and large single ear tag system and dichlorvos (20% AI) in a double tag system gave season-long protection of the ears of cattle against the Gulf Coast tick, Amblyomma maculatun Koch, and the screwworm, Cochliomyia hominivorax (Coquerel). Conversely, dichloros in small single, trimethylphenyl methylcarbamate (3,4,5 and 2,3,5, 75:18) in small double, and dichlorvos, crotoxyphos, and the trimethylphenyl methylcarbamate mixture in large single ear tags provided relatively little if any protection through 5 weeks, and screwworm infestations were frequent in the ears of these cattle. Screwworm infestations were also high at times among untreated control cattle. Horn bands with stirofos gave control of the ticks; horn bands with propoxur gave somewhat less control. However, horn bands were either too loosely or too lightly applied. Ear smears containing 2% dioxathion and 2% Compound 4072 (2-chloro-1-(2,4-dichlorophenyl) vinyl diethyl phosphate) gave some control of ticks.

Colombian Maize Germplasm as Sources of Modifier Genes for Opaque‐21

Despite its proven nutritional superiority, opaque‐2 maize (Zea mays L.) has not been generally accepted in tropical regions and for certain food uses because of its soft endosperm. Modified (more vitreous) opaque‐2 types would be more acceptable. Seven Colombian maize races and a population derived from ETO ✕ USA342 were outcrossed to the homozygous opaque‐2 lines L215 and L216, which have the soft endosperm expression. The crosses were self‐pollinated, and the F2 kernels were classified into three classes over a light. One sub‐family (single ear) of each family was reclassified into four classes on a black‐topped table with a lighted magnifying glass. Chi‐square tests indicated indirectly whether the intermediate classes II or II and III were modified opaque‐2 kernels or if the ratios deviated significantly from 3:1 due to an excess of normal kernels. In the latter case, some homozygous opaque‐2 kernels were so modified that they were phenotypically indistinguishable from normal. A high percentage of intermediates indicated that ETO ✕ USA342, Pira, Puya, and Comun were good sources of modifier genes for opaque‐2. Amagaceno was less promising and conflicting results within our smaller samples of Clavo, Chococeno, and Polio made it impossible to draw definite conclusions about their potential.

Fundamental pitch discrimination for monotic and dichotic two‐tone complexes

Pitch discrimination for the fundamental frequency of a harmonic two‐tone complex was investigated. The stimuli were either monotic, with both tones presented to a single ear, or dichotic, with one tone presented to each ear. An up—down two‐alternative forced‐choice procedure was employed. In each block of trials, seven differences in fundamental frequency around a fundamental frequency of 275 Hz were tested. The procedure was designed to minimize the pitch discrimination cue arising from the partials. The difference in fundamental frequency necessary for 75% correct discrimination (defined as Δf0) was measured as a function of the harmonic number (5–9) and duration (15–250 msec) of the complexes. Two general trends emerged from these data. First, as the duration of the complex tone decreased below 250 msec, performance deteriorated. The rank order of the Δf0's correlated well with duration, but the data were not characterized by a simple reciprocal relationship between Δf0 and stimulus duration. Second, except at the shortest duration tested, discriminability in the dichotic condition was less sensitive than that for the monotic condition. These results are in qualitative agreement with expectations of the pitch saliency of complex tones. [This research was supported by a National Institutes of Health research grant awarded to ASU.]

Varietal traits limiting the grain yield of tropical maize IV. Plant traits and productivity of tropical varieties

Abstract At Tlaltizapan, Mexico, 26 maize varieties with a wide range of various contrasting traits were grown at three plant densities (25, 000, 50, 000, and 100, 000 plants per ha) to clarify the factors currently limiting grain yield. The following results were obtained. 1. Long-duration varieties compared to short-duration varletles tended to be taller and to produce a larger number of leaves, larger LAl, larger TDW, and higher grain yield. No evidence was obtained to indicate that plant type was important for high-yielding varieties. 2. High grain yield was attributable mainly to the larger number of kernels per unit field area. The sink size is possibly the dominant factor controlllng the grain yield, indicating the importance of studies on the yield components. For obtaining high-yielding varieties, it would be important to improve a strain so that a single ear became larger and more tolerant to barrenness at a high plant density.

Residue pitch for a monaural and dichotic two-tone complex

The residue pitch for a two-tone stimulus was investigated. The stimuli were either monaural, with both tones presented to a single ear, or dichotic, with one tone presented to each ear. A two-interval matching procedure was employed. On each trial, a two-tone stimulus, called the standard, was presented in either the first or second temporal interval. In the other interval, an harmonic two-tone complex, which served as a matching stimulus, was presented. The subject was asked to select the interval containing the lower of the two pitches. In each block of trials, the fundamental frequency of the matching stimulus was adjusted until there was no pitch change between intervals. For the monaural stimulus, the pitch shift of the residue obtained from a single subject was very similar to that reported by Smoorenburg [J. Acoust. Soc. Am. 48, 924–942 (1970)]. The pitch shift for the dichotic stimulus closely resembled that of the monaural stimulus when the frequency of the lower component was less than 1500 Hz. With frequencies above 1500 Hz, the dichotic residue pitch was inaudible. The observation that both the dichotic residue and lateralization based on phase differences disappear for stimulus frequencies above 1500 Hz suggests that similar temporal mechanisms underlie both binaural interactions.

Lateral Line Organs and Amphibian Hearing Organs

Lateral line organs are the simplest vibration receptors in vertebrates. They serve to detect water displacement by means of receptor cells and synapses similar to those in hearing organs and may be used as convenient models of function at a cellular level. Epidermal lateral line organs are present in fishes and aquatic amphibia. Each organ contains 10–30 hair cells coupled to the surrounding water via a cupula. During evolution, some lateral line organs in fishes have become enclosed in canals on the head and along the body. Canal organs contain several hundred hair cells which receive a more extensive efferent innervation than those of epidermal organs. The ion content of canal lymph can differ considerably from outside water. Adaptation from aquatic to terrestrial life requires impedance matching at the interface between air and inner ear fluids. In frogs this is achieved by a single middle ear ossicle. Frogs have two hearing organs, the amphibian and the basilar papillae. They differ in their frequency sensitivities and are also different in that hair cells in the basilar papilla have only afferent synapess, while efferent synapses are missing. Basilar papilla primary units still show sharp tuning curves.

Effects of Attenuation of One of Two Channels on Perception of Opposing Pairs of Nonsense Syllables When Monotically and Dichotically Presented

A two-channel listening experiment was carried out in which subjects had to identify each member of pairs of nonsense syllables which coincided in time of onset and offset. The purpose of the experiment was to compare the effect of varying the intensity of the stimuli in one channel when stimuli pairs were presented dichotically (one to each ear) with the effect that occurred when both stimuli were directed monotically to a single ear. We could thus compare the effect of attenuation of one of the two competing speech signals when the competition involved peripheral masking (the monotic condition) with the effect obtained when the locus of masking was exclusively central (the dichotic condition). In the monotic case, the decrement in identification performance was nearly asymptotic with 10 dB of attenuation, whereas in the dichotic case the decrement in performance with attenuation was much less steep, not having reached asymptote at 25 dB of attenuation. These results agree with findings in visual masking studies with respect to the relatively greater importance of intensity difference among stimuli in peripheral masking than in central masking. [This research was supported in part by NSF Grant No. GJ-9.]

Effects of deficit irrigation on some yield characteristics of sweet corn

This study was made to determine the influence of deficit irrigation on drip irrigated sweet corn in 1998 and 1999 in Sanliurfa, Turkey. Water was applied to sweet corn as 100, 90, 80 and 70% of evaporation from a Class A Pan (Epan). Applied irrigation water was 610-876 mm and 612-889 mm in 1998 and 1999, respectively. Plant height, ear length, number of kernels per ear and single fresh ear weight values were the highest at 100% Epan whereas the lowest values were found at 70% Epan in both the years. Water savings were 11.30, 20.89 and 30.36% in 1998 and 10.91, 21.14, 31.15% in 1999 for 90, 80 and 70% of Epan, respectively. The highest fresh ear yields (14.76 and 14.17 t ha-1) were obtained at 100% Epan, whereas minimum fresh ear yields (9.15 and 8.84 t ha-1) were found at 70% of Epan in 1998 and 1999, respectively. Despite the reduction of fresh ear yield, the number of marketable ears at 10% water deficiency (90% Epan) was still high and acceptable for sweet corn production in the Harran Plain of Turkey. Key words: Deficit irrigation, Water saving, Sweet corn, Yield characteristics doi:10.3329/bjb.v37i2.1718 Bangladesh J. Bot. 37(2): 127-131, 2008 (December)

A single ear thresher

A single ear thresher

Release from multiple maskers: effects of interaural time disparities.

Masked thresholds for spondees were measured during 37 binaural listening conditions covering homophasic, antiphasic, parallel time-delayed, and opposed time-delayed listening in the presence of one to four competing maskers at three nominal masker levels (65, 75, and 85 dB SPL). Two of the maskers used were white noise modulated 4 times per second by 10 dB with a 50% duty cycle; the modulation patterns were such that when the noises were combined they produced a continuous white noise. The other two were whole sentences spoken by different male talkers. Masking-level differences (MLD's) re homophasic performance in the same masker complex emerged for every one of the 28 conditions of dichotic listening. MLD's were slightly smaller in the presence of a single competing talker (with or without noise also present) than with two talkers, and MLD's were always largest for the antiphasic conditions (range 4.4–6.8 dB). MLD's for parallel delayed listening (entire masking complex given 0.8-msec lead to a single ear) averaged about 1 dB less than antiphasic conditions, ranging from 3.5 to 6.6 dB. MLD's for opposed time-delay conditions (0.8-msec delays given to all portions of the masker complex but not all masker signals delayed to the same ear) reduced the MLD another 0.6 dB from the antiphasic conditions on the average (range 2.6–6.4 dB). Since subjective separation of competing signals was more definitive during opposed time delays than during either parallel time delays or antiphasic presentation, but since MLD's were smaller during opposed time delays than in the companion dichotic conditions, this study indicates anew that escape from masking and lateralization of signal origin, while depending on common input information, are separate capacities involving two different neurological mechanisms. These findings also suggest that listening in interaurally complex conditions brings into play phenomena that are not covered by contemporary theories of masking.

Effect of binaural and alternating CSS on eyelid conditioning.

Conditioned eyelid performance of a group receiving half their CSs in each ear was not different from a group receiving all the CSs in a single ear. In Exp. 2 a comparison of performance to a (red light) CS was made between a group receiving half their trials to an auditory CS and half to a visual CS as contrasted with a group receiving half their trials to a red and half to a green light CS. Performance to the red light in each group was similar and the results were discussed in terms of stimulus inhibition.

An evaluation of four methods of monitoring simultaneous primary and secondary voice messages.

Four methods of monitoring simultaneous primary and secondary voice messages were investigated in high and low ambient noise environments. Two of the methods used a single earpiece headset and wall speaker, and two methods used a dual earpiece headset with either the primary message in one ear and the secondary message in the other ear, or the primary message in both ears and the secondary message in a single ear. A realistic script and operational setting were used to test the conditions using 54 trained subjects. The dual-headset methods were found to be significally superior to the headset/speaker method in most scoring categories. No significant differences were found between noise levels. The findings are compared with previous research on multimessage monitoring.

Acoustic reflexometry.

A more systematic and rapidly conducted procedure has been devised for auditory stimulation, in the manometric testing of acoustic reflex reactions. The stimuli are brief pulses of changing tones. They are swept from one end of the test frequency scale to the other during a single, uninterrupted recording, at starting amplitudes below or just above reflex threshold. Stimulus strength is raised progressively between repetitive recordings from the same ear. The results have facilitated the comparison of reflex reactions with relation to the stimuli. Wide differences have been found in the effectiveness of particular stimuli and in the appearance of the responses, in a small group of normal subjects. In a few individuals the recorded reactions to some of the stimulus combinations have varied in either a single ear or in both ears. The most extreme type of change has been between momentary protrusion and momentary retraction of the tympanic membrane. The method has yielded consistent results throughout single tests and in repeated tests on the same subject.

THE RELIABILITY OF REPEATED AUDITORY THRESHOLD DETERMINATION.

This paper considers the precision which may be expected in short-term serial measurements of audiometric thresholds. Twelve otologically normal young men were tested on four separate occasions at 1, 2, 3, 4, 6, 8, 0·5, and 1 kc/s. The tests were carried out in a mobile test room installed in a specially constructed vehicle chassis. The acoustic output of the audiometer and ear-phones was measured at intervals throughout the investigation. Output stability with variations of mains supply voltage and drift during the warming-up period of the instrument were also measured. It was concluded that the instrument variation had been extremely slight throughout the investigation. The estimates of variance of repeated threshold determinations on a single ear were found to be 8·5 (dB) 2 at 0·5 kc/s, 6 (dB) 2 at 3 kc/s, and 23 (dB) 2 at 8 kc/s. Differences between consecutive determinations extended to 25 dB. These results were obtained under conditions which practically precluded all sources of variation other than that due to the inherent uncertainty of audiometric measurements. It appears to follow, therefore, that if an apparent drop in auditory threshold in one ear is to be considered as significant evidence ( P = 1%) of a real change, the difference would have to be at least 17·5 dB at the higher frequencies. This level could possibly be reduced to 10 dB if the change occurred simultaneously at both 4 and 6 kc/s.

Stereophonic Listening and Speech Intelligibility against Voice Babble

The utilization of a particular form of stereophonic information was studied with respect to the intelligibility of a single speech source heard in the presence of a voice babble of other speakers. The reception of monosyllabic words, presented against a babble of 1, 2, 4, or 7 talkers, was compared under two listening conditions: (1) In the stereophonic listening condition, one set of background talkers was presented to one earphone, another set of background talkers was presented to the other earphone, and the test words were presented binaurally, in phase; (2) In the control listening condition, only a single set of background talkers, and the test words, were presented to a single ear. The stereophonic advantage, for 50% word intelligibility, ranged from 12 db with 1 background voice per channel to 5.5 db with 7 background voices per channel.

Il Grano Ramoso Ibleo e le sue Forme

Summary In this note about the Hybleous branching corn' and its forms, I refer the results of experiences of the last four years with a particular variety of branching corn, gathered on the Hybleous hills in Sicily. First of all I emphasize the economical importance of this corn, which can give plentiful crops, more than 837–975 times the weight of the seeds. Three different qualities of corn come from the seeds of a same branching ear: corn with single ear, corn with branching ear, and corn with branching and single ears on the same plant. From another experience it results that from the seeds of the above named qualities, gathered separately, each kind sown separately in separate beds, have produced, in each bed all three forms of the above mentioned corn, as in the preceding generation. In another experiment of a different order (1951–52 e 1952–53) have been sown, in an advanced season, seeds of branching corn in a flower-bed set apart, more than three months later than the ordinary sowing time. This delay in date has yielded noticeable effects, among which the most interesting are: the life cycle of corn has been shortened and obliged to develop itself in three months and half only. The seed's summer rest has been prolonged three months over and above it's normal time. The seeds themselves have not able to avail themselves of the winter cold and the low temperatures. Corn's seeds and plants are exposed to the quick approach of the hot and dry season which has hastened the plant's growth and the ripening of the ears. Many particular conditions of the surroundings have resulted, which have disturbed the internal conditions of the plant, and forced the plants to react and to yeld not more branching ears, but only single and scarce ears. A transformation of form has been produced by the influence of the external causes. This recalls to mind the phenomenon of eredità scossa.