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Before changing settings, look at the default values. Always change one setting at a time and try small changes first! To help other users, please share your favourite settings in a comment on the support page here. If you own an iPhone 4, there are special settings to improve the audio, available here.

Activate: activates the application. You need to activate the program by selecting this setting. When activated, the mode button will work.

General (Mode Settings): When "on" the current audio mode is available; when "off" the mode is unavailable to the user.

Audio Settings (Global) Sample freq: The audio sampling frequency used. CD quality is 44100 samples per second. When changing this value, halve it each time, e.g.: 44100, 22050, 11025. You may need to alter the delay to make the audio sound smooth. Changing the sampling freq affects the audio filters, so you will need to adjust filter values to compensate.

Audio Settings (Global) iPhone delay: The delay from input to output in seconds. Although iStethscope Pro has very fast real-time filtering, if you encounter problems with audio, you should try increasing the delay. The iPhone delay value is only used when running on an iPhone. If using an iPod, change the iPod delay setting instead.

Audio Settings (Global) Ignore last second: ignores the last second of recorded audio when ON, in order to remove the noise of moving the iphone from the chest.

Audio Settings (Filters and Volume, Low-pass filter) Alpha: The alpha value determines the frequency cut-off for the low-pass filter. A higher value means fewer high frequencies are heard (good for removing hiss and crackle).

Audio Settings (Filters and Volume, High-pass filter) Beta: The beta value determines the frequency cut-off for the high-pass filter. A higher value means fewer low frequencies are heard (good for removing rumble).

Audio Settings (Filters and Volume, Volume and Amplification) Volume: sets the initial volume level when first switching to this audio mode (value should be between 0 and 10).

Audio Settings (Filters and Volume, Volume and Amplification) Amplification: sets how loud the audio will be (louder is not always better, as the sound may become clipped and distorted).

Audio Settings (Filters and Volume, Volume and Amplification) Auto volume control: activates or deactivates the AVC, which temporarily reduces the volume for over-loud sounds (by dynamically altering the filters).

Audio Settings (Filters and Volume, Volume and Amplification) Max level: sets the audio level at which AVC is activated - higher means louder sounds are permitted (value should be between 0 and 32768).

Audio Settings (Filters and Volume, Accelerometer, Global) Update rate: sets the global, application-level accelerometer update rate per second. Faster devices can support faster update rates, making the accelerometer more accurate, but also affecting the shake-activation and the update speed of the phonocardiograph. Slower devices may require a slower update rate to avoid interfering with the audio processing that runs in parallel.

Audio Settings (Filters and Volume, Accelerometer audio mode) Sine wave freq: sets the mapping from G-forces to audible tones. Changing this value will change the pitch of the tones you hear for different G forces.

Help: provides a URL to these web pages.

Medical Trial (Medical Collection): When on, the following settings are activated: only heartbeat filtered mode is active, sample freq is 44100, the delay is 0.1, alpha is 2, beta is 1.001, amplification is 0.375, volume is 2, AVC is off, and the medical collection email address and email body is auto-filled. For more details of the medical trial, please visit

Warning! This mode has AVC turned off, so there is no protection against loud sounds. You may damage your ears or your audio equipment if you have the volume too high in this mode. You are advised to practise using the normal listening modes and only activate the Medical Collection option briefly in order to participate in the trial.

Note that the settings are only valid for iPhone 3G devices; the microphone in the iPhone 4 has an inferior ability to pick up low frequencies and so please do not use the Medical Trial option with your iPhone 4 because the audio data will not be of sufficient quality.