Tunable active sound absorbers
OwnerMaximilian Hans Hobelsbergerinventor
Life of this patent
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Abstract
The sound absorber is a combination of an acoustical transformer with an actively simulated acoustical impedance. The acoustical transformer transforms the high active impedance into a low impedance at the mouth of the transformer. The absorber is tuned by changing the active impedance.
Claims21
Active sound absorber, comprising
- a) an acoustical transformer,
- b) a device for simulation of an acoustical impedance, which comprises
- c) an electroacoustical transducer with a membrane, wherein said membrane is acoustically coupled to said acoustical transformer,
- d) pressure sensing means, being arranged within said acoustical transformer substantially close to said transducer's membrane, for measuring the air pressure and producing signals indicative of said air pressure,
- e) driving means, for moving said transducer's membrane with a momentary membrane speed which depends on said measured air pressure according to a predetermined impedance function, wherein said driving means receive said signals produced by said pressure sensing means,
- wherein said acoustical transformer and said device for simulation of an acoustical impedance are dimensioned such that said sound absorber is an acoustical resonator with predetermined resonance frequencies.
Method for tuning the resonance frequency of a resonant sound absorber, comprising the step of acoustically coupling an acoustical transformer to a device for simulation of an acoustical impedance, which further comprises the steps of
- a) arranging an electro-acoustical transducer with a membrane, such that said membrane is acoustically coupled to said acoustical transformer,
- b) arranging pressure sensing means within said acoustical transformer , for measuring the air pressure and producing signals indicative of said air pressure,
- c) arranging driving means, for moving said transducer's membrane with a momentary membrane speed which depends on said measured air pressure according to a predetermined impedance function, wherein said driving means receive said signals produced by said-pressure sensing means,
- d) dimensioning said acoustical transformer and said driving means such that the device works as acoustical resonator at predetermined resonance frequencies,
- e) tuning said resonance frequencies by adapting said driving means.
Method for transforming the acoustical impedance of a device for simulation of an acoustical impedance to other values,
- comprising the step of acoustically coupling an acoustical transformer to a device for simulation of an acoustical impedance, which further comprises the steps of
- a) arranging an electro-acoustical transducer with a membrane, such that said membrane is acoustically coupled to said acoustical transformer,
- b) arranging pressure sensing means within said acoustical transformer, for measuring the air pressure and producing signals indicative of said air pressure,
- c) arranging driving means, for moving said transducer's membrane with a momentary membrane speed which depends on said measured air pressure according to a predetermined impedance function, wherein said driving means receive said signals produced by said pressure sensing means,
- d) dimensioning said acoustical transformer and said driving means such that the device works as acoustical resonator at predetermined resonance frequencies.
Dependencies are inferred from the claim text.