Research has suggested that representational and perceptual systems draw upon some of the same processing structures, and evidence also has accumulated to suggest that representational formats are malleable by instructions. Very little research, however, has considered how nonspeech sounds are internally represented, and the use of audio in systems will often proceed under the assumption that separation of information by modality is sufficient for eliminating information processing conflicts. Three studies examined the representation of nonspeech sounds in working memory. In Experiment 1, a mental scanning paradigm suggested that nonspeech sounds can be flexibly represented in working memory, but also that a universal per-item scanning cost persisted across encoding strategies. Experiment 2 modified the sentence-picture verification task to include nonspeech sounds (i.e., a sound-sentence-picture verification task) and found evidence generally supporting three distinct formats of representation as well as a lingering effect of auditory stimuli for verification times across representational formats. Experiment 3 manipulated three formats of internal representation (verbal, visuospatial imagery, and auditory imagery) for a point estimation sonification task in the presence of three types of interference tasks (verbal, visuospatial, and auditory) in an effort to induce selective processing code (i.e., domain-specific working memory) interference. Results showed no selective interference but instead suggested a general performance decline (i.e., a general representational resource) for the sonification task in the presence of an interference task, regardless of the sonification encoding strategy or the qualitative interference task demands. Results suggested a distinct role of internal representations for nonspeech sounds with respect to cognitive theory. The predictions of the processing codes dimension of the multiple resources construct were not confirmed; possible explanations are explored. The practical implications for the use of nonspeech sounds in applications include a possible response time advantage when an external stimulus and the format of internal representation match.