ForeFlight Mobile offers audible alerts as follows:
500' AGL Alerts - The 500’ AGL alert is a simple callout that triggers when you descend through 500’ AGL after having been above 1,000’ AGL. The alert will only sound once every 60 seconds and is automatically disabled if your groundspeed is less than 40 knots.
Cabin Pressure Altitude - When your aircraft cabin pressure altitude passes 12,000’ MSL and 25,000’MSL. (Requires iPad/iPhone or external device equipped with a barometric sensor)
Destination WX Frequency Alerts - The destination weather frequency callout provides you with your destination airport’s weather frequency (whether ATIS, AWOS, or ASOS) as you near the airport.
Device Disconnect - The Device Disconnect alert is triggered if the Bluetooth or Wi-Fi connection to a portable or panel-mounted device that ForeFlight supports is lost. This allows you to take appropriate action to restore the connection, to switch to a backup device (if available), or to continue the flight knowing that the previously connected device is no longer available. The alert is only triggered if your groundspeed is above 40 knots or if your device does not have a GPS fix.
New Flight Loaded from Panel - If connected to installed avionics that can send flight plans to ForeFlight (such as Garmin Connext devices), and “Auto-Receive Panel Flight Plans” is enabled in More > Settings, any time ForeFlight receives and loads a new flight plan from the panel it will display a “New Flight Plan Loaded From Panel” message.
Runways - When nearing or entering a runway.
Runway Final Approach Alert - For any runway that you are approaching based on your altitude, vertical speed, track, and whether you are within 4nm of the runway threshold.
Sink Rate - Above 2,500’ AGL (or when AGL is not known), the alert is triggered if your descent rate exceeds -4,000‘ per minute. At 2,500’ AGL, the alert is triggered if your descent rate exceeds -3,000’ per minute. Between 2,500’ AGL and 500’ AGL, the descent rate required to trigger the alert decreases linearly along with altitude, down to a threshold of -1,500’ per minute. At 500’ AGL the alert is triggered if your descent rate exceeds -1,500’ per minute.
Terrain/Obstacle Alerts - When GPS Accuracy is good the Terrain/Obstacle Alert detects and warns of threatening obstacle and terrain using visual and audio alerts that display app-wide, not just on the Maps view. When nearby to airports the alert sensitivity automatically adjusts to reduce nuisance alerts. Requires Pro Plus subscription or higher, and that Obstacle data and Terrain data have been downloaded.
TFR Alerts - Audio alerts will warn you if your present track will take you inside (or over/under) a known TFR within the next 5 minutes, even if you don’t have the TFR map layer turned on. Four different alerts are possible based on your position relative to the TFR: “TFR Ahead”, “TFR Below”, “TFR Above”, and “Inside TFR”.
Traffic - When ForeFlight determines a traffic target will be within 1.3NM and +/- 1,200’ of your position in less than 25 seconds, an audible alert sounds. Audible traffic alerts require ForeFlight to detect ADS-B Ownship. ADS-B Ownship is the process of identifying a traffic target as your aircraft. ADS-B Ownship detection requires an ADS-B receiver or onboard Wi-Fi.
Transition Altitude - When climbing or descending through the transition altitude.
Weight & Balance - You will get differing audible tones when a change is made to your weight & balance and your CG falls within or outside of the CG limits.
You can trigger a sample audio alert by tapping on MORE > SETTINGS and then toggle "Speak All Alerts" OFF and back ON. When the alert is playing you can press the Volume Up or Volume Down toggle on the side of the iPad or iPhone to adjust the volume of the alert.