Listen To Your Heart

Set a target heart-rate zone. Inside it you hear nothing at all - your music or podcast plays normally. Drift out of it and the audio ducks under a chime whose rhythm tells you how far off you are, and which way, without looking at anything. HOW IT SOUNDS - Direction is pitch: bright high pips mean you are above your zone, low dark pips mean below. - Distance is rhythm: the further out you are, the more pips in the group and the faster it repeats, from one slow pip every four seconds just outside the zone to four fast pips when you are far out. - Nothing ever gets louder. The alert ducks your audio briefly and your podcast or playlist comes straight back. WHERE IT PLAYS Tap Start on your iPhone and it keeps sounding the alert with the screen off and the phone in your pocket, for as long as your workout lasts, until you tap Stop. Or tap Start on your Apple Watch instead and it plays…