GB2191916A - Sound processing and reproduction system - Google Patents

Abstract

An acoustic signal is input to a microphone 1 in sound reproducing apparatus (eg. in a toy) and re- issued from a loudspeaker 2 at a higher pitch by delta modulation. When the apparatus is incorporated in a doll, a solid state memory 7 stores speech from a child (after the modulation stage) and a serial to parallel conversion thereof for subsequent read-out, processing and amplification. The output from the loudspeaker is then the same as the child's speech but at a higher pitch and it is delayed. <IMAGE>

Description

SPECIFICATION Sound reproducing apparatus This invention relates to sound reproducing apparatus.

According to this invention there is provided sound reproducing apparatus comprising an input transducer operative to convert an input acoustic signal into an input electrical signal; processing means operative to process the input electrical signal to form an output electrical signal representative of the input acoustic signal and an output transducer operative to convert the output electrical signal into an output acoustic signal which is the input acoustic signal.

In a preferred feature of this invention the apparatus is arranged for the processing of input speech, music or any audio frequency sound to provide pitch transposition of the sound by modifying the input signal. Such apparatus can be used, for example, to accept single words or short phrases spoken by a child, and then reproduce these sounds, either automatically or when prompted in some way, in the voice of a baby or young child, thus simulating the interaction between a mother and child when the child is learning to talk.

The pitch transposition is achieved according to this invention, by converting the input signal to digital form at a one clock frequency and retrieving it at a higher clock frequency.

This invention will now be described by way of example with reference to the drawings, in which: Figure 1 is a block schematic circuit diagram of apparatus according to the invention; Figure 2 is a diagram illustrating the process of delta modulation as used in the apparatus of Fig. 1; and Figure 3 is a circuit diagram of a delta modulation unit operating in accordance with Fig.

2.

The apparatus to be described is for incorporation in a toy doll where the apparatus functions to receive an input acoustic signal in the form of speech from a child playing with the doll, and to return the speech changed in pitch upwards whereby the child can play a mother and baby game with the doll.

The apparatus comprises an input transducer in the form of a microphone 1 adapted to be mounted in the upper part of the abdomen of the doll, and an output transducer in the form of a loudspeaker 2 adapted to be mounted at the entrance to the head cavity of the doll whereby the head cavity can serve as a sound amplifier for the output acoustic signal which will appear to come from the doll's mouth.

The microphone 1 serves to convert an input acoustic signal in the form of speech into an analogue input electric signal which is supplied by way of an amplifier 3 to a sound (in this case voice) activated trigger 4 and a delta modulation unit 5. The trigger 4 serves to ensure that the apparatus is not activated by general background noise, but only by normal speech from a maximum range of about two metres.

The output of the unit 5 is supplied via a serial to parallel converter 6 to a 64K random access memory 7 which is capable of storing about two seconds of input acoustic signal.

The output of the memory 7 is supplied via a parallel to serial converter 8, a demodulator 9 and an output electrical signal amplifier 10, to the loudspeaker 2.

Operation of the apparatus is controlled by a clock and digital controller 11 which is triggered by the trigger 4 and supplies control signals to the unit 5, the memory 7 and the converters 6 and 8.

The above apparatus apart from the microphone 1 and loudspeaker 2, can be provided on a printed circuit board substrate measuring about 11 cm by 7.5 cm, together with a battery power supply.

The apparatus functions after triggering off the trigger 4 by a suitable input voice signal, to process the input voice signal and reissue it from the loudspeaker 2 transposed upwards in pitch by about the musical interval of a fifth whereby the owner of the input voice will think that their words are being repeated by a younger person. This pitch transposition is effected by conversion of the input signal to digital from at a particular clock frequency and subsequently increasing the clock frequency when the digital information is retrieved from the memory such that it is converted to a bit stream of higher frequency prior to being processed by the demodulator Section 9. This serves to shift the pitch of the original input signal in much the same way as that of replaying a 33 r.p.m. record at 45 r.p.m.

Referring now to Figs. 2 and 3 also, the unit 5 functions as a delta modulator, and in particular as a continuously variable shape delta modulator.

As shown in Fig. 2, the incoming analogue signal Vx from the amplifier 3 is compared with a reference signal Vy which is either continuously increasing or decreasing in level, under the control of the clock signal from the controller 11. If at comparison times the incoming signal Vx is higher than the reference signal Vy then the output signal Vmod from the unit 5 is a binary '1', while if it is lower, then the output signal Vmod is a binary '0'. In this way increments and decrements in the level of the incoming analogue signal Vx are converted into a stream of binary bits. For example, if the incoming signal Vx is level, as shown to the right in Fig. 2, then the output signal Vmod from the unit 5 will be 01010101 etc.

Fig. 3 shows a block diagram of a delta modulation unit which functions as set out above.

The unit comprises a comparator to which the incoming analogue signal Vx and the reference signal Vy are supplied, and a flip-flop device FF which serves to capture the output of the comparator at a fixed sampling rate determined by the clock signal from the controller 11. The reference signal Vy is derived from the output of the flip-flop by means of a feed-back network comprising a resistor RA and a capacitor CA which together form an integrator which converts the bit stream at the Q output of the flip-flop to give the reference signal Vy. The Q output of the flip-flop also provides the output signal Vmod from the circuit.

The converter 6 serves to convert the output signal from the unit 5 into 8-bit binary words for storing in the memory 7, while the converter 8 serves to reconvert the binary words from the memory 7 into a bit stream which corresponds to that produced by the unit 5 but delayed by a time which is a function of the length of the memory 7 and the clocking rate.

The binary bit stream from the converter 8 is converted to an analogue signal by the demodulator 9 for supply by way of the amplifier 10 to the loudspeaker 2.

The above described apparatus provides a highly cost-effective way for the inclusion of digital solid state electronics in toys and games, or other devices.

It will be appreciated that the memory 7 can be made as large as is necessary to store a required length of speech. Otherwise, the storage capacity can be enhanced without increasing the size of the memory by decreasing the frequency of the clock signal from the controller 11 controlling operation of the apparatus, although in this case there will be a corresponding decrease in the quality of sound produced.

The above described apparatus can be constructed using discrete components or can be integrated into a single LSl or VLSI circuit.

Claims (7)

1. Sound reproducing apparatus comprising an input transducer operative to convert an input acoustic signal into an input electrical signal; processing means operative to process the input electrical signal to form an output electrical signal representative of the input acoustic signal; and an output transducer operative to convert the output electrical signal into an output acoustic signal which is the input acoustic signal.

2. Apparatus as claimed in Claim 1, in which the processing means functions by delta modulation.

3. Apparatus as claimed in Claim 1 or Claim 2, in which the processing means stores the output electrical signal prior to supply thereof to the output transducer.

4. Apparatus as claimed in any preceding claim, in which the input transducer is a microphone.

5. Apparatus as claimed in any preceding claim, in which the output transducer is a loudspeaker.

6. Apparatus as claimed in any preceding claim, including an acoustic switch operative by a particular acoustic input signal to initiate operation of the apparatus.

7. Sound reproducing apparatus as described and with reference to the drawings.

7. Apparatus as claimed in any preceding claim, in which the input signal is modified before being produced as an output signal to transpose the pitch of the sound.

8. Apparatus as claimed in Claim 7, in which the input signal is converted to digital form at one clock frequency and produced at a higher clock frequency.

9. Apparatus as claimed in any preceding claim, in which the input acoustic signal is a human voice.

10. Apparatus as claimed in any preceding claim, in the form of a battery-powered selfcontained unit for mounting in a talking toy.

11. A talking toy including apparatus as claimed in any preceding claim.

12. A talking toy as claimed in Claim 11, in which the apparatus additionally serves to control movement of other parts of the toy.

13. A talking doll in accordance with Claim 12, in which said other parts are the mouth and/or eyes of the doll.

14. Sound reproducing apparatus substantially as hereinbefore described with reference to the drawings.

15. A talking toy substantially as hereinbefore described with reference to the drawings.

CLAIMS Amendments to the claims have been filed, and have the following effect: New or textually amended claims have been filed as follows:

1. Sound reproducing apparatus comprising an input transducer (1) operative to convert an input acoustic signal into an input electrical signal; processing means (5) arranged to subject the input electrical signal to delta modulation to form an output electrical signal representative of the input acoustic signal; and an output transducer (2) operative to convert the output electrical signal into an output acoustic signal which is the input electrical signal.

2. Apparatus according to Claim 1 characterised in that the processing means (5) is arranged to subject the input electrical signal to continuously variable shape delta modulation.

3. Apparatus according to Claim 1 or 2 characterised in that the processing means (5) is arranged to reissue the input acoustic signal as an output acoustic signal which is at a pitch about one fifth of a musical interval higher.

4. Apparatus according to any preceding Claim characterised in that the processing means (5) is arranged to convert an input electrical signal to digital form at one clock frequency and to produce it at a higher clock frequency.

5. Apparatus according to any preceding Claim characterised in that the input acoustic signal is a human voice.

6. Apparatus according to any preceding Claim characterised in that it is located in a toy.