Electroacoustic device for hearing needs including noise cancellation

• US 5,117,461 A
• Filed: 07/10/1990
• Issued: 05/26/1992
• Est. Priority Date: 08/10/1989
• Status: Expired due to Term

• Current Assignee: MNC, Inc.
• Original Assignee: MNC, Inc.
• Inventors: Moseley, William T.
• Primary Examiner(s): Isen, Forester W.
• Application Number:
  US07/532,323
• Time in Patent Office: 686 Days
• Field of Search: 381/72, 381/71, 381/163, 381/150
• US Class Current: 381/72
• CPC Class Codes: A61F 11/145 electric, e.g. for active noise reduction
• CPC Class Codes: G10K 11/17821 characterised by the analysis of the input signals only
• CPC Class Codes: G10K 11/17827 Desired external signals, e.g. pass-through audio such as music or speech
• CPC Class Codes: G10K 11/1783 handling or detecting of non-standard events or conditions, e.g. changing operating modes under specific operating conditions
• CPC Class Codes: G10K 11/17857 Geometric disposition, e.g. placement of microphones
• CPC Class Codes: G10K 11/17861 using additional means for damping sound, e.g. using sound absorbing panels
• CPC Class Codes: G10K 11/17873 using a reference signal without an error signal, e.g. pure feedforward
• CPC Class Codes: G10K 11/17875 using an error signal without a reference signal, e.g. pure feedback
• CPC Class Codes: G10K 11/17885 additionally using a desired external signal, e.g. pass-through audio such as music or speech
• CPC Class Codes: G10K 2210/108 Communication systems, e.g. where useful sound is kept and noise is cancelled
• CPC Class Codes: G10K 2210/1081 Earphones, e.g. for telephones, ear protectors or headsets
• CPC Class Codes: G10K 2210/3045 Multiple acoustic inputs, single acoustic output
• CPC Class Codes: G10K 2210/3214 Architectures, e.g. special constructional features or arrangements of features
• CPC Class Codes: H04R 1/1008 Earpieces of the supra-aural or circum-aural type
• CPC Class Codes: H04R 1/1083 Reduction of ambient noise active noise reduction per se G10K11/175; protective devices for the ear, e.g. providing acoustic protection A61F11/06

Abstract

A device for performing electroacoustic functions including noise cancellation, hearing aid, communication interface, headset, feed for recording device, and headphone functions. The device includes composite transducers connected to a control unit. The composite transducers can be mounted on a headband and are configured to include input transducers for converting acoustic waves into electrical signals for processing by a control unit, and output transducers for converting the processed electrical signals to processed sound waves. The control unit includes an inverter/amplifier and a mixer/output amplifier for inverting the electrical input and controlling the gain for either adjusting the gain to maximize a noise cancellation function or increasing the gain beyond the minimum level heard by the ear to a desired level for a hearing aid function. Connectors for connecting recorders and a boom microphone, and function selection switches are provided by the control means for connecting circuit components of the control unit selectively for performing the above functions. The input and output transducers have oppositely oriented diaphragms mounted in a common plane to provide an inverted acoustic wave in real time for combining with and substantially cancelling an incoming acoustic wave. In this embodiment, an isolation wall means may also be incorporated to prevent sound from the output transducer from propagating back into the input transducer. In a second embodiment, the input and output transducer are both oriented in the same direction toward the user'"'"'s ear canal.

Claims

1. An electroacoustic device for cancelling sound waves in a bounded ear canal, comprising:

an input transducer for converting sound waves incident on a pickup surface of the input transducer into corresponding input electrical signals;

an output transducer for converting output electrical signals into corresponding sound waves which emanate from a diaphragm surface of the output transducer into the bounded ear canal, said output transducer defining a boundary of the bounded ear canal;

a transducer frame to which said input transducer and said output transducer are fixed so that said pickup surface of said output transducer are in substantially the same plane, the input transducer and the output transducer being independently mounted on the transducer frame such that the movement of the pickup surface relative to the transducer frame is primarily in response to incident sound waves, said transducer frame defining another boundary of said bounded ear canal; and

a control means for receiving the electrical signals from the input transducer and for generating the output electrical signals to the output transducer, the output electrical signals being substantially 180 degrees out of phase with respect to said sound waves incident on said pickup surface of said input transducer so that sound waves in said bounded ear canal are substantially cancelled;

said diaphragm of said output transducer being mounted to direct sound waves primarily toward said ear canal and said pickup device of said input transducer being mounted to face in the same direction relative to the ear canal when said device is mounted on a user'"'"'s ear.

2. An electroacoustic device for cancelling sound waves in a bounded ear canal, comprising:

an input transducer for converting sound waves incident on a pickup surface of the input transducer into corresponding input electrical signals;

an output transducer for converting output electrical signals into corresponding sound waves which emanate from a diaphragm surface of the output transducer into said bounded ear canal, said output transducer defining a boundary of said bounded ear canal;

a transducer frame to which said input transducer and said output transducer are fixed so that said pickup surface of said input transducer and said diaphragm surface of said output transducer are in substantially the same plane, the input transducer and the output transducer being independently mounted on the transducer frame such that the movement of the pickup surface relative to the transducer frame is primarily in response to incident sound waves, said transducer frame defining another boundary of said bounded ear canal; and

a control means for receiving the electrical signals from the input transducer and for generating the output electrical signals to the output transducer, the output electrical signals being substantially 180 degrees out of phase with respect to said sound waves incident on said pickup surface of said input transducer so that sound waves in said bounded ear canal are substantially cancelled;

said transducer frame including an inner surface for disposition adjacent a user'"'"'s ear and an outer surface and wall means being mounted over said outer surface and carried by said transducer frame said wall means having a disc shaped wall portion, said outer surface having a selected surface area and said wall portion extending substantially coextensively with said outer surface to cover said surface area.