The lateral-line organ of killifish is shown to be sensitive to a linear function of water displacements associated with the near-field of sound sources, with the displacement probably being the most important factor rather than velocity or acceleration. The near-field effect is discussed and is shown to be important not only for the lateral-line organs but also for the acoustical and vestibular organs. It is emphasized that the near-field effect introduces considerable complications into the study of the acoustico-lateralis system, and is of conceptual importance for the theory of hearing and the study of schooling fish.

The model of binaural interaction proposed by B•k•sy in 1930 which has received very little attention in modern theories is re-examined in the light of recent anatomical and physiological findings. A modified model is proposed in which time and intensity are mapped independent of each other in the accessory nuclei of the superior olive; excitatory and inhibitory neural signals interact at the accessory nucleus neurons, giving rise to time-intensity trade. The behavior of the model is in qualitative accord with psychophysical and physiological observations.

An experiment is described in which time and intensity differences of 2-kc high-pass clicks were mutually offset to produce sound images centered in the head. Binaurally correlated and uncorrelated clicks were used, and the trade was tested at 10-70 db SL. The results show that generally the two types of clicks behave similarly, and that up to 60 db SL, at least, as over-all intensity increases, the time difference compensating a given intensity difference (in db) decreases. A function is derived describing what is interpreted as a physiological intensity-to-time conversion. The place of such a conversion in lateralization is discussed.INAURAL interactions lead to a number of psychologically striking phenomena. A central aspect in many of these is the formation of a unitary sound image which occupies a restricted region of the observer's perceptual space. For instance, when a listener, in an acoustic field generated by a localized source, samples the field at two points by means of his two ears, the resultant neural signals are combined to yield a percept projected near the physical location of the source. Furthermore, the subjective image is often identified with the source; this process is usually referred to as "localization." A localized image also appears when the binaural stimuli are delivered through earphones. Here, however, the image appears near or even inside the head and is not usually associated either with any external source or with the earphones. To preserve this distinction, the earphone case is referred to as "lateralization."The foregoing remarks mean that some binaurally heard stimuli may produce a sound image different from that produced by either stimulus heard monaurally. From the psychophysical point of view, of course, such differences arise from interaural relations which are not available from either stimulus alone. One of the general aims of the work reported in this paper is to identify certain interaural relations with one aspect, namely, "centering" of the image. A secondary aim is to deduce from the results something about the physiological mechanisms responsible for the formation of the image. In the latter effort, of course, we rely heavily upon anatomical and neurophysiological work from other sources. Inferences and models resulting from such work had important bearing upon the design of our experiment. BINAURAL INTERACTIONOF COMPLEX STIMULI 77,5 •ot been studied; and, from our preliminary result 5 and that of Leakey, Sayers, and Cherry, ø it appears that coherent signals are not required. What is required, apparently, is a temporal cue to each ear provided by a sharp onset or a discontinuity, or generally, some lowfrequency prominence in the wave-form envelope.These cues need not be embedded in correlated stimuli.

No abstract

The development of specialized auditory and vibration-sensitive structures in vertebrates, is marked by the occurrence of several complementary organs. In fish and in aquatic amphibia, lateral line organs which are sensitive to water displacement are found on the body and head (Harris and van Bergeijk, '62). In the minnow, the sacular-lagenar complex within the membranous labyrinth is believed to be capable of sound reception (von Frisch, '38). In the ray, the papilla neglecta and portions of the saccule and utricle are responsive to low-frequency vibrations (Lowenstein and Roberts, '51). In higher vertebrates, exceedingly sensitive labyrinthine structures for detecting air-borne sound occur. This type of organ finds its highest expression in the cochlea of mammals. The development of cochlea-like structures can be traced from a primitive organ called the basilar papilla which is found in amphibia. In the amphibia alone among vertebrates another organ occurs in the labyrinth which because of its structure and location has been considered to be an auditory organ. This is the amphibian papilla. Recent electrophysiological results (Frishkopf and Goldstein, '63; Frishkopf and Geisler, '63) show that in the bullfrog (R. catesbeiana) both the amphibian and basilar papillae function as sensitive auditory transducers with very different response characteristics. The present anatomical study was undertaken in order to aid in the interpretation of these physiological results, by presenting in comprehensive form those features of the bullfrog's ear which seem most directly concerned with the reception of sound stimuli. The main emphasis has been placed on a detailed description of the amphibian papilla and, to a lesser extent, of the basilar papilla; their innervations and their connections to the external auditory system are also touched upon.J. MORPH., 114: 43-58. METHODS AND MATERIALSTadpoles (stages 28-33, Witschi, '56) and adults of Rana catesbeiana were used in this study. Tadpoles were fixed by immersion in Bouin's or Zenker's fixatives, and a few were perfused through the heart with Helly's fixative. Adults were perfused with one of these fixatives, usually Zenker's. Whole heads of tadpoles and excised bony labyrinths of adults were decalciiied and embedded in paraffin, sectioned serially at thicknesses of 10-20 g , and stained with Mallory triple stain. For detailed study of the nerve fibers innervating the ear, fixation with 1% phosphatebuffered osmium tetroxide (Millionig, '61 ) was used. Fixation with osmium tetroxide was begun by injecting the fixative into the partly opened saccule of the anesthetized frog. The membranous labyrinth of the inner ear was then excised (within 30 minutes of the initial injection) and immersed in the fixative for approximately one hour. Embedding in paraffin, serial sectioning and mounting without further staining followed. Data from these different preparations were obtained in a variety of ways which are best discussed in connection with the specific data.Dissections of fresh an...