Abstract: A hearing aid is identified by storing a first binary code in the hearing aid as a first identification code, storing a second binary code in the hearing aid as a default code, and replacing the default code with a second identification code if a second hearing aid is used by the person using the first hearing aid. The identification code includes a bit indicating for which ear the hearing aid is intended. If two hearing aids are used, the identification code of the first hearing aid is substituted for the default code in the second hearing aid and vice-versa, thereby pairing the first hearing aid with the second hearing aid and indicating that there are two hearing aids needed, even if one hearing aid should become lost or inoperative.

Abstract: A hearing aid is identified by storing a binary code in the hearing aid, receiving a transmitted code, reading out a subset of bits from the stored binary code, and comparing the transmitted code with the subset for identification. The reading step preferably reads the lowest order nibble, byte, or word of the binary code. In accordance with another aspect of the invention, a charger for the hearing aid, a controller for the hearing aid, and a programmer for the hearing aid store the identification codes for two way communication among the devices.

Abstract: Data is transferred to and from a hearing aid by transmitting an audible carrier having a frequency greater than 5 kilohertz, modulating the carrier with data, and detecting the modulated carrier in the hearing aid with a narrow band filter. The frequency is in a region where impairment occurs and there are many other sounds, thereby masking the communication, yet not interfering with it.

Abstract: Hearing loss is evaluated and compensated by applying a hearing aid having substantially uniform frequency response across several bands of the audible spectrum, evaluating hearing loss in each band using the hearing aid, programming the hearing aid to compensate for the loss in each band, and using the hearing aid to compensate for hearing loss. The evaluation is preferably preceded by substantially canceling noise in the ear canal using the electronics in the hearing aid. In accordance with another aspect of the invention, the evaluation is not performed if a hearing aid is not recognized by a hand held programmer but the user has the option of programming a hearing aid with existing data. The evaluation optionally includes providing background noise in the ear not being evaluated to reduce the chance of cross-coupling during the evaluation.

Abstract: A hearing aid having a plurality of frequency bands is calibrated by evaluating the response of the hearing aid in each band and programming the hearing aid to produce a specific sound pressure level in each band, thereby providing a calibrated instrument that can be used for both evaluation and compensation of hearing loss. The sound pressure levels are preferably the same for each band. The evaluation step is preferably performed at the center frequency of each band.

Abstract: A hearing aid having a rechargeable battery and a charger for charging the battery include means for transferring data means for transferring data unidirectionally or bidirectionally between the hearing aid and the charger using either a magnetic field, light, or sound. The hearing aid includes means for detecting the charge state of a battery and for sending a signal to the charger indicative of the charge state. For acoustic coupling, the charger includes a microphone and a speaker and also includes a chamber for receiving at least a portion of the hearing aid.

Abstract: Voice activity is detected by comparing an in band signal with an out of band signal. If the ratio of the signals is greater than a predetermined amount, then voice is detected.