The alveolar trill is one of the most difficult sounds to be produced in Spanish and as a result is acquired later in development. Research suggests that the alveolar trill is acquired and developed between the ages of three and six years. Some children acquire an adult-like trill within this period and some fail to properly acquire the trill. The attempted trill sound of the poor trillers is often perceived as a series of taps owing to hyperactive tongue movement during production.