telling them in a disinterested voice
disinterested
/(ˌ)dis-ˈin-trə-stəd/
adjective
not having the mind or feelings engaged : not, interested
no longer interested
free from selfish motive or interest : unbiased
husband and wife become disinterested in each other
indifferent unconcerned incurious aloof detached disinterested mean not showing or feeling interest. indifferent implies neutrality of attitude from lack of inclination, preference, or prejudice. unconcerned suggests a lack of sensitivity or regard for others' needs or troubles.
verb
to cause to regard something with no interest or concern