(Pocket-lint) - The US Patent & Trademark Office has recently published a series of three patents, filed by Apple that refer to "earbuds with biometric sensing". The three patents are for three different pairs of headphones: an in-ear pair with an ear hook, a conventional pair of in-ears and a pair of over-ears.

In the patents, there is a note to say that at least one of the built-in sensors will make contact with the tragus, the small bit on the inside of your ear in front of the ear canal.

By coming into contact with the tragus, the biometric sensor will be able to collect health information via a photoplethysmogram sensor (PPG), which shines a light onto the tragus and and measure the reflectivity. This information can reveal heart rate, temperature and VO2, the maximum rate of oxygen consumption.

Apple already employs a similar technique in the Apple Watch to measure the wearer's health information, and as the Watch is in constant contact with the wrist, the information can be considered quite accurate. It's unlikely an earbud will have the same constant contact with the ear during wearing, so the accuracy of the data will be questionable.

It's also thought that Apple's new headphones could offer noise-cancellation thanks to microphones that can block external sounds. The headphones would then provide varying levels of noise-cancellation, so you could let some external noise in, for example, when riding a bike in traffic, so you're still aware of your surroundings.

Of course, these are just patents for now, so it may be some time before we see any real products come to market, but it's clear Apple is taking health tracking tech very seriously.

Writing by Max Langridge.