Methods and apparatus to dynamically generate audio signatures adaptive to circumstances associated with media being monitored are disclosed. An example apparatus includes a media content analyzer to detect a watermark encoded in media monitored by a meter. The apparatus includes a media environment analyzer to estimate an amount of background noise in an environment in which the media is monitored by the meter. The apparatus further includes a signature scheme selector to select a first signature scheme from among a plurality of signature schemes to generate monitored signatures of the media. The first signature scheme is selected based on the amount of background noise. The apparatus also includes a signature generator to generate a first monitored signature of the media based on the first signature scheme.