Acoustic analysis of a respiratory therapy system

A device for generating a patient and/or system status indication with a respiratory therapy system configured to deliver respiratory therapy to a patient, the respiratory therapy system comprising a flow generator configured to generate a supply of pressurized air along an air circuit to a patient interface, the device comprising:

• a sensor configured to generate a sound signal representing a sound in the air circuit;
• and
• a controller configured to:
• process the sound signal representing a sound in the air circuit to obtain cepstrum data;
• generate a time series of delay estimates based on acoustic signatures in the cepstrum data, wherein each of the acoustic signatures represents a reflection of sound from the patient interface along the air circuit;
• analyse variation in the time series of delay estimates;
• and
• generate one or more output indicators based on the variation, the one or more output indicators concerning patient and/or system status.

Apparatus comprising:

• means for generating a sound signal representing a sound in an air circuit of a respiratory therapy system, the respiratory therapy system comprising a flow generator configured to generate a supply of pressurized air from an outlet along the air circuit to a patient interface;
• means for processing the sound signal representing a sound in the air circuit, to obtain cepstrum data;
• means for generating a time series of delay estimates based on acoustic signatures in the cepstrum data, wherein each of the acoustic signatures represents a reflection of sound from the patient interface along the air circuit;
• means for analysing variation of the time series of delay estimates;
• and
• means for generating one or more output indicators based on the variation, the one or more output indicators concerning patient and/or system status.

A method of one or more processors for generating a status indication about a patient interface associated with a respiratory therapy system configured to deliver respiratory therapy to a patient, the respiratory therapy system comprising a flow generator configured to generate a supply of pressurized air along an air circuit to the patient interface, the method comprising:

• processing a sound signal representing a sound in the air circuit, to obtain cepstrum data;
• separating an acoustic signature from the cepstrum data, the acoustic signature representing a reflection of sound from the patient interface along the air circuit;
• estimating an internal delay of the acoustic signature, wherein the internal delay is a delay between two portions of the acoustic signature representing reflections from respective components of the patient interface separated by a mask tube;
• repeating the processing, separating, and estimating to generate a time series of estimates of the internal delay;
• analysing the time series of internal delay estimates;
• and
• generating one or more output indicators based on the analysing, the one or more output indicators concerning patient interface status.

A device for generating a status indication about a patient interface for a respiratory therapy system configured to deliver respiratory therapy to a patient, the respiratory therapy system comprising a flow generator configured to generate a supply of pressurized air along an air circuit to the patient interface, the device comprising:

• a sensor configured to generate a sound signal representing a sound in the air circuit;
• and
• a controller configured to:
• process the sound signal representing a sound in the air circuit, to obtain cepstrum data;
• separate an acoustic signature from the cepstrum data, the acoustic signature representing a reflection of sound from the patient interface along the air circuit;
• estimate an internal delay of the acoustic signature, wherein the internal delay is a delay between two portions of the acoustic signature, each portion representing a reflection from a corresponding component of the patient interface separated by a mask tube;
• repeat the processing, separating, and estimating to generate a time series of estimates of the internal delay;
• analyse the time series of internal delay estimates;
• and
• generate one or more output indicators based on the analysing, the one or more output indicators concerning patient interface status.

Apparatus comprising:

• means for generating a sound signal representing a sound in an air circuit of a respiratory therapy system, the respiratory therapy system comprising a flow generator configured to generate a supply of pressurized air from an outlet along the air circuit to a patient interface;
• means for processing the sound signal representing a sound in the air circuit, to obtain cepstrum data;
• means for separating an acoustic signature from the cepstrum, the acoustic signature representing a reflection of sound from the patient interface along the air circuit;
• means for estimating an internal delay of the acoustic signature, wherein the internal delay is a delay between two portions of the acoustic signature, each portion representing a reflection from a corresponding component of the patient interface separated by a mask tube;
• means for repeating the processing, separating, and estimating to generate a time series of estimates of the internal delay;
• means for analysing the time series of internal delay estimates;
• and
• means for generating one or more output indicators based on the analysing, the one or more output indicators concerning patient interface status.