Frequency capping is a metric used to deliver the best possible campaign results without impacting listener experience. The cap represents the maximum number of times a certain ad can be heard by a listener in a given period. For example, an ad should not be heard by the same listener more than x times each day.
AudioGO uses a predefined frequency capping which aims for a good balance between ensuring sufficient available inventory and a good listener experience.
The share between impressions and reach is indirectly affected by sizing goals for a given audience size. You can read more about how to set up the perfect campaign for awareness or reach in this blog post about Audience Guide, a feature that helps you set up the best targeting for your campaign.