GB1248937A - A method of and apparatus for translating voice frequency sound signals into a form audible and comprehensible to severely deaf persons - Google Patents

Abstract

1,248,937. Hearing aids. E. BIONDI and L. BIONDI. 16 Oct., 1968 [28 Dec., 1967], No. 49052/68. Headings H4J and H4R. In deaf aid apparatus, sound signals (Fig. 1) are converted into A.F. electrical signals and these are sampled for time durations #t at spaced time intervals T. The sample signals e<SP>1</SP>(t) are held by a holding circuit 5 (Fig. 3) for time T (Fig. 2) and the held signals e<SP>11</SP>(t) are filtered and converted to sound signals. The apparatus is useful for deaf people having residual hearing e.g. within the range 200 to 1000 Hz. In one embodiment the apparatus comprises a microphone 1, Fig. 3, an input amplifier 2, a filter 3 and a sampling switch 4 for converting input signals e(t) into pulses e<SP>1</SP>(t). A holding circuit 5 produces the output signals e<SP>11</SP>(t). A low-pass filter 6 delivers the filtered signal via an amplifier 7 to a device for converting electrical signals into sound signals. In a first modification, a store (9), Fig. 4 (not shown), is inserted between the sampling switch 4 and holding circuit 5 and cyclically stores the pulses e<SP>1</SP>(t) at a frequency Is, the store (9) being read at frequency f 1 . The store (9) has, for example, 2 or 4 storage elements and f s may be either greater or less than f 1 . Alternatively the sampled signals from sampling device 4(Fig. 3) are switched by an electronic switch (10), Fig. 5 (not shown), into two identical lines (5, 6, 7, 8), one for each ear. In another arrangement the switch (10) is replaced by a cyclic store (11), Fig. 6 (not shown), having a relatively large number of storage elements. The store (11) serves both as an electronic switch (10) (Fig. 5) and as a cyclic store (9) (Fig. 4).