Manfred Zollner

Method for the electrical stimulation of the auditory nerve and multichannel hearing prosthesis for carrying out the method

In the exemplary embodiments, the sound signals are converted into electrical signals, which are wirelessly transmitted to an implanted receiver, and from the latter, electric stimuli in electrode channels are brought to act on the auditory nerve. The transmission proceeds in the time division multiplex technique in such a manner that the electrical signals are subjected to a pulse modulation and are transmitted in an HF-channel. Thus, the receiver can be reduced with regard to the volume of its construction as well as with regard to its energy requirement. The disclosed method and hearing prostheses for its realization are particularly suited for attending to the needs of the extremely hard of hearing.

Method and apparatus for generating electrocutaneous stimulation patterns for the transmission of acoustic information

In an exemplary embodiment, the point of departure is that of a substitute signal system for deaf individuals which codes acoustical signals, in particular speech sound, into electrocutaneous stimulation patterns. Current pulse patterns serve as substitute signals which, via skin surface electrodes, e.g. on the forearm, bring about sensory patterns which can be interpreted as speech information. To this end, the sound signal is separated with band pass filters into e.g. twelve component signals characteristic for the recognition of speech, whose levels are converted into pulse durations, whereby the dependency of the sensation intensity upon the stimulation parameters is taken into account. The mean frequencies of the band pass filters are associated with a corresponding number of locations on the forearm (i.e. in the present example twelve). A simulation of lateral inhibition suppresses irrelevant spectral components and thus acts in a selectivity-increasing (or enhancing) fashion. It is thereby possible that, after only approximately fifteen hours of practice, ten monosyllabic words are correctly recognized with a reliability of approximately 95% by means of the sensor patterns which are to be transmitted in accordance with the disclosure. The disclosed method and apparatus for its realization are particularly suited for use in hearing prostheses for deaf individuals.

Method for generating acoustical speech signals which can be understood by persons extremely hard of hearing and a device for the implementation of said method

In the illustrated embodiments, the signals to be transmitted are converted into electrical signals and are divided by means of filters into a plurality of frequency bands. The envelopes of the signals coming out of the filters are then employed for the modulation of tones. Finally, the original tones and the modulated tones are supplied to the hearing-impaired person as an audio signal. To this end, the disclosure provides that the original signal to be transmitted is transmitted together with the modulated tones, and that the ratio of the volumes of the original tones and those of the modulated tones is set to a ratio which is comfortable for the hearing-impaired person. The transmission of the modulated tones is at least partially interrupted for voiced sounds. Standard ear sets or implanted devices with direct electrical transmission of the signals to the auditory nerve can be employed for transmission to the hearing-impaired person. Disclosed methods and devices are particularly employable as a hearing aid for persons who are extremely hard of hearing or who have suffered total hearing loss.

Method for generating acoustical voice signals for persons extremely hard of hearing and a device for implementing this method

In an exemplary embodiment, the signals to be transmitted are converted into electric signals and resolved into a multiplicity of frequency bands by means of filters. The signals coming from the filters are then employed for the modulation of tone signals. Finally, original tones are supplied to the person hard of hearing together with the modulated tones as the auditory signal. To this end, the disclosure provides that the resolution ensues into at least three frequency bands and that the frequencies of the modulated tones are adapted to the residual frequency band of the person hard of hearing and that all of the signals to be transmitted are transmitted together with the modulated tones and that the ratio of the loudness of the original tones and that of the modulated tones is set at a ratio which is useful for the person hard of hearing. For transmission to the person hard of hearing, standard earpieces can be employed or implanted devices with direct electric transmission of the signals to the auditory nerves. Disclosed methods and devices are particularly employable as a hearing aid device for persons who are very hard of hearing or who have total hearing impairment.

Application of auditory contours to speech quality measurements

For the development of instrumental speech quality measures it is important to model human auditory signal processing. The ITU‐T standard P.861 for telephone transmission quality, however, neither takes into account the time‐frequency resolution of the human ear nor its masking properties. Moreover the abstraction or contorization processes occurring in speech perception are disregarded. Terhardt proposed to use spectral pitch as the primary auditory contour. In our approach it is derived from the part‐tone time‐pattern (PTTP) originally conceptualized by Heinbach [Acustica 67, 242–256 (1988)]. The PTTP is extracted from an aurally adequate spectral analysis. A new instrumental method based on differences of auditory contours will be presented. The results will be compared with other instrumental methods and with data from subjective listening tests.

Betriebsverhalten von realen Wandlern

Wahrend in den Kap. 4 und 5 die Funktionsprinzipien und Grundgleichungen der Wandler angegeben wurden, sollen in diesem Kapitel einige typische Betriebsgrosen wie Frequenzgang, Rauschen, Verzerrungen, Richtcharakteristik diskutiert werden. Zum Verstandnis ist die Kenntnis der beiden vorhergehenden Kapitel notig, soweit sie den speziellen Wandlertyp betreffen.

Hörbarkeit von Übertragungsfehlern

In Abschn. 1.6.3 haben wir die Horflache mit dem Schalldruckpegel als Ordinate und mit der logarithmisch aufgetragenen Frequenz als Abszisse kennengelernt. Auch die Kurven gleicher Lautstarke bzw. gleicher Lautheit wurden in dieser Ebene dargestellt. Nachdem die Empfindungsgrose fur die Lautstarkeempfindung, die Lautheit, und deren Abhangigkeit vom Schallpegel ebenfalls in Abschn. 1.6.3 beschrieben wurde, soll im folgenden derjenige Anteil der vielfaltigen Eigenschaften des Gehors wenigstens in wesentlichen Grunddaten diskutiert werden, der fur akustische Informationsubertragung, wie sie in der Nachrichtentechnik durchgefuhrt wird, wichtig ist. Den Lesern, die sich mit den Eigenschaften des Gehors ausfuhrlicher beschaftigen wollen, mag der Hinweis auf weiterfuhrende Literatur weiterhelfen.