HEARING PROTECTOR

• US 20110019834A1
• Filed: 03/23/2009
• Published: 01/27/2011
• Est. Priority Date: 03/26/2008
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M China Limited (3M Company)
• Inventors: Fransson, Henrik
• Granted Patent: US 8,995,676 B2
• Time in Patent Office: Days
• US Class Current: 381/71.6
• CPC Class Codes: A61F 11/145 electric, e.g. for active noise reduction
• CPC Class Codes: G10K 11/17823 Reference signals, e.g. ambient acoustic environment
• 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 11/17837 by retaining part of the ambient acoustic environment, e.g. speech or alarm signals that the user needs to hear
• 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 11/17881 the reference signal being an acoustic signal, e.g. recorded with a microphone
• CPC Class Codes: G10K 2210/1081 Earphones, e.g. for telephones, ear protectors or headsets
• 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 hearing protector comprises two protective muffs (1) with passive noise damping, a microphone (3) disposed in at least the one protective muff (1) and connected to an analog and a digital signal processing device (5 and 7, respectively), the signal processing devices (5, 7) being connected to loudspeakers (4) disposed interiorly in the protective muffs (1) for extinguishing interior noise in the protective muffs (1). The analog signal processing device is rehearsed for processing non-repeatable noise, while the digital signal processing device is rehearsed for processing repeatable noise. According to the invention, a further microphone (8) is disposed outside the passive noise damping and is connected to the digital signal processing device for tracing and locking onto repeatable noise.

Claims

1. A hearing protector which comprises:

a protective muff (1) provided for each ear of a wearer, with at least a certain passive noise damping, a microphone (3) disposed interiorly in the protective muff and connected to an analog signal processing device (5) and a digital signal processing device (7), the signal processing devices being connected to at least one loudspeaker (4) disposed interiorly in the muff for emitting sound for extinguishing noise in the protective muff, and the analog signal processing device being substantially rehearsed for processing non-repeatable noise while the digital signal processing device is substantially rehearsed for processing repeatable noise, characterised by a second microphone (8) disposed outside the passive noise damping and connected to the digital signal processing device (7).

2. The hearing protector as claimed in claim 1, characterised in that the digital signal processing device (7) is rehearsed to give priority to signals from the second microphone (8) as regards tracing and identifying repeatable noise.

3. The hearing protector as claimed in claim 1 or 2, characterised in that the second microphone (8) is disposed in an enclosure (2) on the protective hood but outside its passive noise damping.

4. The hearing protector as claimed in claim 3, characterised in that the digital signal processing device (7) is disposed in the enclosure (2).

5. The hearing protector as claimed in claim 1, characterised in that the second microphone (8) is disposed to sense whether a total noise level is sufficiently high for the second microphone (8) to engage in active noise canceling.

6. The hearing protector as claimed in claim 1, characterised in that the second microphone (8) controls the analog signal processing device (5).

9. The hearing protector as claimed in claim 1, characterised in that the hearing protector is disposed to be automatically deactivated if it has been removed from the head of a wearer for a given length of time.

10. The hearing protector as claimed in claim 1, characterised in that a wearer can elect to reduce the damping for a given desired ambient noise whose frequency is known.

11. The hearing protector as claimed in claim 1, characterised in that the digital signal processing device (7) is passive with respect to random noise.

12. The hearing protector as claimed in claim 1, characterised in that a second loudspeaker (9) for a communications radio is provided interiorly in the protective muff (1).

7. The hearing protector as claimed in claim 7, characterised in that the second microphone (8) is disposed to deactivate the analog signal processing device (5) in response to a level of external noise.

8. The hearing protector as claimed in claim 8, characterised in that the hearing protector is automatically deactivated if the level of external noise has been sufficiently low for a given period of time.