The above screenshot is obtained from Chrome. Other browsers may show something slightly different. The two bottom controls may not be displayed in certain cases.
The top control "A" is the playbar provided by the browser. It allows to play, pause, change volume, mute, and move the time slider through the piece
The second control "B" is the section slider. It allows to identify a specific section of the piece to be played. The two handles "C" and "D" mark the beginning and the end of the section to be played. Initially, the two handles are set at the beginning and at the end of the piece, so the section identified corresponds to the whole piece. Then you can drag each handle to the desired position on the slider and mark the beginning and the end of the desired section. Time labels help to identify the desired position. To precisely set a handle to a certain time value, move the handle near to the desired time value, then double-click the time label to manually enter the desired time value. The handle nearest to the time value you entered will precisely move to that time.
The pushbutton on the left of the section slider enables or disables the section player, so you can toggle between playing the whole piece or just the section identified.
The pushbutton on the right of the section "E" enables or disables the loop player. If the loop player is enabled, the section (or the whole piece, depending whether the section player is enabled or not) is played and, when the end is reached, it is played again from the beginning. If the loop player is disabled, playing stops at the end of the section (or of the whole piece), so you have to manually click the button on the playbar to restart the player.
The third control "F" is the tempo slider. It allows to slow down or speed up music. The slider controls “tempo” from 50% (very slow) to 150% (very fast) of the nominal speed (100%). The “tortoise” pushbutton on the left side of the slider reduces “tempo” in 5% steps, while the “hare” pushbutton on the right side of the slider increases “tempo” in 5% steps. Large speed variations with respect to the nominal speed may result in noisy or distorted audio performance. This depends on the specific browser you use. Currently, the best performance is offered by Chrome and Safari, followed by Mozilla Firefox. The performance of Microsoft Internet Explorer and Edge is a little bit worse.