With two ears, you can tell if a sound is approaching you from the right, left or front. You are even able to determine how far a sound is to the right or to the left.
With one ear, you are likely to hear every sound only from the hearing side. If you repeat the experiment and listen to the sounds from different directions, you will find that you cannot determine the direction the sound is coming from – not even whether the sound is coming from the right or left.
The ability to establish where a sound is coming from is tested in special rooms. The room in which Michael performs the experiment with you is a so-called Anechoic Chamber.
We recorded the sounds you hear in the experiments in such a room, with a technique called binaural recording [1]. For this, a mannequin head is equipped with outer ears made of rubber and microphones are placed in the ear canal. The test we prepared for your experience is directly derived from methods used in clinical trials with hearing solutions and in scientific experiments which explore the fascinating details of hearing with two ears.
The exact method is described in detail by Paul van de Heyning [2]. A group of clinical researchers compiled a collection of methods which can be used to quantify the benefits of implanted hearing solutions in patients with single-sided deafness, but also in users of bilateral cochlear implants (https://www.ncbi.nlm.nih.gov/pubmed/28319951).