Ensure you have the following equipment:

Total Volume = Stethoscope Volume + Mic/Input Volume
​Target: Aim for approximately 75% peak level during heartbeats

Use the Windows search function to find and open Control Panel.

Select Hardware and Sound → Sound.

In the Sound window, click the Recording tab.

This is the input connected to your Thinklabs One stethoscope.
Click Properties.

In the Microphone Properties window, select the Levels tab.

Press any key to power on the Thinklabs One.
Set the volume to 3–4 out of 10 as a starting point.

Place the Thinklabs One over the heart.
If headphones are connected, listen while adjusting levels.

Adjust the Mic slider to 10–25.
Aim for the level bars reaching ~75% of maximum during peak heartbeats.

Pro Tip:
​

If using headphones, first set the stethoscope volume to a comfortable listening level, then adjust the Mic volume to reach the ~75% peak target.

Click the Apple icon in the top-left corner and select System Preferences.

In System Preferences, click Sound.

Click the Input tab and select the USB Audio Device.

Adjust the Input Volume slider to the midpoint as a starting position.

Press any key to power on the Thinklabs One.
Set volume to 3–4 out of 10.

Place the Thinklabs One over the heart and listen while adjusting levels.

During peak heartbeats, aim for about three-quarters of maximum on the input level scale. Avoid clipping.

Pro Tip:
Many combinations of stethoscope volume and input volume can produce good results. Adjust the stethoscope volume first for comfort, then fine-tune the Input slider.

Avoid distortion:
Never allow levels to reach maximum during peak heartbeats — this causes static distortion. Keep levels at approximately 75% of maximum.