Patent ID: 7577267

Claim:
A hearing aid, comprising: an input converter for acquiring an input signal and converting the input signal into an electrical signal; a signal processing unit for processing and amplifying the electrical signal, the amplification of the electrical signal depending on a frequency included in the input signal; an output converter for generating and outputting acoustic output signals; a power source for supplying power to the hearing aid; and an evaluation unit configured to determine a property indicative of an operational condition of the power source, the property chosen from the group consisting of a current capacity and an expected remaining operating time, and the output converter is configured to generate an acoustic output signal based on the determined property, wherein the acoustic output signal consists of a tone having a rising frequency when the property indicative of the operational condition of the power source is above a pre-defined threshold value, and further wherein the acoustic output signal consists of a tone having a falling frequency when the property indicative of the operational condition of the power source is below the pre-defined threshold value.