How to record chest sounds with good sound quality

It is important to record your chest sounds with good sound quality. High quality recordings will help your doctor to correctly detect any possible abnormalities.  

Follow the below techniques to ensure good sound quality.

Getting ready to start recording:

• Remove any cables and the smartphone case before using Stethophone.
• Ensure Bluetooth headphones are connected and working, and the smartphone volume is set to about 50%.
• Find a quiet room to minimize background noise (cars, talk, music, even the fridge and washing machine produce a lot of distracting noise).

Before you start recording:

• Select your body position, as it often influences heart sounds, blood flow, and the clarity of the recording. In general, it can be any position that makes you feel relaxed and comfortable and allows you to hear your heart and lungs clearly.
• Hold the smartphone gently near the top to avoid hand muscle trembling and movement during the recording.
• Choose the body spot for recording and press the bottom of the smartphone to your bare skin. Ensure that there is no obstruction between the smartphone and your bare skin, and your clothes don’t touch the smartphone.
• Ensure the bottom of the smartphone fits snugly and evenly against the body surface without gaps.
• Ensure the smartphone is perpendicular to the point of contact.
• Avoid placing the microphone directly over ribs, as sound quality can be poor when blocked by bone.

Figure 1. Smartphone placement

• Use light, even pressure to press the smartphone to your body. The presence of chest hair may require firmer pressure to eliminate any potential interference. Excessive pressure may cause unwanted sounds.
• Listen to the chest sound through your headphones. Listening will help you to find the best spot on your body. Adjust the position of the smartphone slightly until you can hear strong, clear sound.

While recording:

• The quality of your breath is important during the recording. See recommendations How to breathe during the recording.
• Contact with your body during all 20 seconds of the recording should remain steady without movement to avoid frictional noise.
• Continue listening to the chest sounds with your Bluetooth headphones to monitor the recording process.