Systems and methods for serving online content based on user engagement duration

A system to serve online content, comprising:

• one or more processors and memory to:
• identify a request for an additional content item for presentation with a first content item via audio output on an access device;
• determine, based on consumption data or the first content item, a duration for the additional content item;
• select, based on the duration, a second content item for presentation via audio output on the access device;
• transmit the first content item to the access device for output;
• and
• provide the second content item for output by the access device.

A method of serving online content, comprising:

• identifying, by one or more processors, a request for an additional content item for presentation with a first content item via audio output on an access device;
• determining, by the one or more processors, based on consumption data or the first content item, a duration for the additional content item;
• selecting, by the one or more processors based on the duration, a second content item for presentation via audio output on the access device;
• transmitting, by the one or more processors, the first content item to the access device for output;
• and
• providing, by the one or more processors, the second content item for output by the access device.