SPARQL/22

SELECT
  ?speaker
  ?speakerLabel
  ?count
  ?languages
# Get pairs of speaker and languages from the list of audios
WITH {
  SELECT DISTINCT
    ?speaker
    ?language
  {
    ?audio
      prop:P4 ?language;
      prop:P5 ?speaker.
  }
} AS %speakers
# Get the count of languages per each speaker
WITH {
  SELECT
    ?speaker
    (COUNT(?speaker) AS ?count)
  {
    INCLUDE %speakers.
  }
  GROUP BY ?speaker
  ORDER BY DESC(?count)
} AS %countOfLanguagesRecordedPerSpeaker
# Get the maximum number of languages per each speaker
WITH {
  SELECT
    (MAX(?count) AS ?maxNumberOfLanguagesRecorded)
  {
    INCLUDE %countOfLanguagesRecordedPerSpeaker.
  }
} AS %maxNumberOfLanguagesRecorded
# Get those speakers whose count equals the maximum number of
# languages
WITH {
  SELECT
    ?speaker
    ?count
  {
    INCLUDE %countOfLanguagesRecordedPerSpeaker.
    INCLUDE %maxNumberOfLanguagesRecorded.
    FILTER(?count = ?maxNumberOfLanguagesRecorded).
  }
} AS %speakersWithMostNumberOfLanguagesRecorded
# Get the languages of those speakers that have recorded audios in the
# most number of languages
WITH {
  SELECT
    ?speaker
    (GROUP_CONCAT(?languageLabel; SEPARATOR = ", ") AS ?languages)
  {
    INCLUDE %speakersWithMostNumberOfLanguagesRecorded.
    ?speaker
      prop:P4 [
        rdfs:label ?languageLabel
      ]
    FILTER(LANG(?languageLabel) = "en").
  }
  GROUP BY ?speaker
} AS %languagesOfSpeakersWithMostNumberOfLanguagesRecorded
{
  INCLUDE %speakersWithMostNumberOfLanguagesRecorded.
  INCLUDE %languagesOfSpeakersWithMostNumberOfLanguagesRecorded.
  ?speaker rdfs:label ?speakerLabel.
  FILTER(LANG(?speakerLabel) = "en")
}